Model Engine Maker

Help! => Hints, Tips & Tricks => Topic started by: Ramon on May 06, 2013, 10:51:16 PM

Title: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 06, 2013, 10:51:16 PM
Hi everyone.

We all know this subject has been prominent of late and this new thread will hopefully cover it in depth.  I have posted it under this banner for no reason other than it doesn't seem to fit anywhere else - perhaps there should be a new heading - Workshop Techniques? If it's felt it should be moved elsewhere however please do

Rod - 'Tangler' and Jo have specifically asked if the method used could be described and several others have endorsed that. Before we get going I would like to stress that this is very much how I carry this out and definitely not to imply that it is the way.
Any comment, constructive or not is welcome - the actual process is basic but the manner in which some approach the manufacture of laps does differ. I have a pretty fixed way of going about it as quite simply 'it works'. Not technically trained in the process the skill and experience has been acquired however by carrying it out on occasion over a number of years and particularly so on these small diesels.

Based on what's been done over the years hopefully there will be plenty of images to convey the process but that said  it's not going to be dealt with in one post  :o so bear with it  ::)

Okay then - who was it said 'start at the beginning and go on to the end'.

After the Linley mill was acquired it was not long before it became apparent that the means to sharpen cutters would be required. Just about this time the Quorn appeared in ME and so I set out to build one. At that time I had had no formal machining training and had only been model engineering for a short few years. I was however in a club and said club had a member  - one Len Evans. You may perhaps recall I have made reference to him before  ::)

I discussed with him what I saw was a major problem namely the means of getting four bores the exact fit for the lower bars on the Quorn. Len's answer was immediate - bore them. But I lacked the confidence to guarantee the size. " In that case you need a lap" and so began my experience with lapping. Following his instructions I bored the holes to within 2 or 3 thou (I was 'imperial' at that time ;)) and made my first lap which I still have, unused since those first four 1" bores....

(https://lh6.googleusercontent.com/-AGpE2Iaz2nk/UYExJ_7ZIxI/AAAAAAAAHiM/CKSN7TDix2I/s640/DSCF2723.JPG)
The lap material is copper wrapped around a steel mandrel that is cut away like a D Bit. The copper is silver soldered to the leading edge of the 'D' and the cut away portion is inserted to enable expansion via a grub screw. Once soldered it was held in the lathe and turned to about 1-2 thou down on the bore size - the anular gap so created being neccessary to contain the lapping compound. If I remember correctly and it is a long time ago valve grinding paste was used  - I can't remember much else except that it was not difficult to do - the lap removed the metal far quicker than anticipated and the finish and size of the bores were far better than hoped for. Those first tentative steps had proved successful and a new skill had been acquired albeit one that would be some years before being put into use again.

Though it's thought that the design was one described by Len Mason it's not certain where the the method of making this type of lap was acquired from - there's no claim for originality that's for sure but many similar laps have been made over the years since that first one and all have proved extremely successful and easy to use. Despite the fact that they don't open radially they retain their circularity even after considerable use though they do tend to become a little eccentric to the shaft but as this process is all carried out as a floating operation that does not appear to have any detrimental effect.

These are some of the laps made in the same fashion since that time all, except that first one for the Quorn, made for model engine cylinder bores. The actual method of manufacture will get covered later.
(https://lh6.googleusercontent.com/-wbGyfw2wn6E/T-9jBxTvFuI/AAAAAAAAGkU/SD5kur9ap_s/s640/DSCF0792.JPG)

The larger one to the left was made for these....the liners and cylinder barrels for the Bentley BR2.
(https://lh4.googleusercontent.com/-GlTiIjhKb10/UYExifd5tsI/AAAAAAAAHjM/DejBJq6Oq9g/s640/DSCF2743.JPG) 

Neccessary to overcome a big oversight on my part :o that will have to wait until tomorrow I'm afraid - it's been a long day and I'm feeling quite whacked  :old:

Regards for now - Ramon
Title: Lapping (and honing) - some techniques for discussion
Post by: ths on May 06, 2013, 11:20:26 PM
Thanks for that ,Ramon. Your laps look so much more long lasting than the ones I have made before, an external one for the GHT sensitive drill quill, and an internal one for ETW's Argus oscillator! The latter was done, I'm sure, just to do it. The internal hone was done to a Len Mason design that can be found in 'Using the Small Lathe'. They both worked extremely well, I used valve grinding paste, coarse and fine, and a few scratches remain on the quill from the use of the coarse. I have since acquired a set of diamond grinding pastes in syringes, but have yet to use them.

Looking forward to more of this strangely satisfying topic!

Cheers, Hugh.
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Don1966 on May 06, 2013, 11:51:07 PM
Ramon, you have my full attention. I know you showed these once before, but I am glued to more of you teaching. I await your making of the lap and demo of its use. Thanks much for taking the time to demo them for us, much appreciated.

Don
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: b.lindsey on May 07, 2013, 12:28:48 AM
Nice start on this topic Ramon...folowing along with interest however long it takes.

Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 07, 2013, 01:05:19 AM
Oh you can count on me taking copious notes!

 :praise2: :praise2: :praise2: :praise2: :praise2:

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: swilliams on May 07, 2013, 03:52:46 AM
Oh you can count on me taking copious notes!

Me too

Steve
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: tel on May 07, 2013, 07:10:32 AM
And I'm right here with the crowd. :ThumbsUp:
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jo on May 07, 2013, 07:56:39 AM
Thanks for doing this Ramon  :ThumbsUp:,

Waiting with baited breath for the next installment.

Jo
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Stuart on May 07, 2013, 08:15:45 AM
Got the popcorn out ready for an interesting and informative thread



Stuart  :old:
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 07, 2013, 08:39:07 AM
Hi 'Guys'  I don't know how to tell you this but we are going to have to wait  bit - I just went to repond to BronxFigs post and my computer crashed. Just went ping and the screen went out :o

I've got the old laptop back on stream but of course all the recent pics taken including quite a few yesterday when lapping started on the Etas are in the other computer and 'double' of course I didn't have it backed up

Hope it's not anything too serious as theres an awful lot of pics on there not to mention several thousand words for the forthcoming article -

I'm now off to take it too the sick bay - in the meantime bear with me, I'll keep you posted.

What a time for this to happen - we really do need a smiley for 'gutted'

regards for now - Ramon

Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jo on May 07, 2013, 08:50:51 AM
Would this meet your needs Ramon:

(http://smileys.on-my-web.com/repository/Sad/sad-012.gif)

Jo
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Maryak on May 07, 2013, 09:04:08 AM
Ramon

(http://smileys.on-my-web.com/repository/Sad/crying-022.gif)

(http://smileys.on-my-web.com/repository/Sad/sad-025.gif)

(http://smileys.on-my-web.com/repository/Confused/redface-oops-6.gif)

(http://smileys.on-my-web.com/repository/Computer/blue-screen-of-death.gif)

Take your pick  :slap:

Sorry for your troubles
Bob


Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 07, 2013, 09:25:47 AM
Hmmm! something like that I guess - just got back from the shop - I await with bated breath.

Stay positive I tell myself - they assure me they should at least be able to reclaim the files - ah! - just keep smiling :)

Regards - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Stuart on May 07, 2013, 09:51:52 AM
(http://smileys.on-my-web.com/repository/Sad/sad-026.gif)


get the hard disk out shove it in a USB hd caddy and use your laptop to access the important data


I bet you know their as two kinds of people that do backups those that do, and those that will


Commiseration's on the PC I still have plenty of popcorn left

Stuart
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 07, 2013, 10:11:53 AM
Thanks for the advice Stuart but hope you won't mind if I deline and leave it well alone - lathes and oil and other sundry related items are one thing - computers are another ball game  ::)

Don't overdo the popcorn  :)

regards - Ramon

PS yes I do have  a back up - just not recent enough  ::) Stable gates and horses spring to mind
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 07, 2013, 11:43:51 AM
Hi 'Guys'  I don't know how to tell you this but we are going to have to wait  bit - I just went to repond to BronxFigs post and my computer crashed. Just went ping and the screen went out :o

I've got the old laptop back on stream but of course all the recent pics taken including quite a few yesterday when lapping started on the Etas are in the other computer and 'double' of course I didn't have it backed up

Hope it's not anything too serious as theres an awful lot of pics on there not to mention several thousand words for the forthcoming article -

I'm now off to take it too the sick bay - in the meantime bear with me, I'll keep you posted.

What a time for this to happen - we really do need a smiley for 'gutted'

regards for now - Ramon

No worries mate!.....best of luck with the repair!
Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: mhirst121 on May 07, 2013, 03:15:56 PM
Hope they get it sorted for you Ramon, I must admit to the same mistake, not backing up often enough and the hard drive went bang !!
Can`t wait for the next update on this subject.

MartinH
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Alan Haisley on May 08, 2013, 03:51:12 AM
At least it lets me get in on the beginning. Just have to hope that there is a middle and end.
I can do boring kinda close, but if I ever want to make a really good IC engine I know that I must learn to  :paranoia: :paranoia: :paranoia: laps.
Alan
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 08, 2013, 11:27:14 AM
Hope the "puta" thing is getting sorted out Ramon!....Can't wait to read your posts on the subject!....got a Wallaby to build! :ThumbsUp:

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: zeeprogrammer on May 08, 2013, 12:15:01 PM
Just catching the train. This is going to be very interesting.
Thanks for taking the time Ramon.
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: GWRdriver on May 08, 2013, 05:03:22 PM
I await an education myself.  My lapping experience is limited to a single shaft (or column - for a tapping stand) and I was greatly pleased with the results.  I turned it between centers and worked it with an external lap which was little more than a short piece of split copper tube.   By working short sections of the shaft at a time, and continuously miking, I got it all within 2/10ths of target dimension.

I had hoped for a much better finish on the shaft but I had only one abrasive grit, which while "fine" was too course for a good final finish.  Which brings me to my real moan, which is that in the past I've had difficulty finding very fine compounds (ie, beyond normal automotive grits) in less than large tins, far too much to have sitting around between occasional lapping jobs.  I look forward to learning what others do about this.  BTW, Ramon I will be in Suffolk in June, specifically near Sudbury, to visit the ancestral pile.
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jasonb on May 08, 2013, 05:33:23 PM
I'll give a source of the grits when Ramon gets to that stage
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 08, 2013, 10:16:11 PM
Hi 'Guys' - (that always includes you Jo BTW ;))

Pleased to say the old computer is back up and running with no loss of data. They couldn't explain the 'breakdown' - certainly wasn't a loss of power as the fan was working albeit somewhat faster but they could find no problem internally.  ::)

Well I hope this can live up to all your expectations  :o - I'll do my best :)

Though the process is simple in itself there are a lot of variables - as mentioned previously varying methods of making laps as well as differing types of abrasive compounds and no doubt individual preferred techniques but it all revolves around one principle and that is introducing an abrasive between two surfaces at least one of which is moving in order to remove material to acheive a better fit and/or improve the finish.
In it's most basic form it's none other than laying a sheet of wet and dry paper on a smooth flat surface such as a surface plate and moving a part over it to reduce it's thickness usually by a minimal amount and that is where lapping becomes a useful skill - to remove minimal amounts of material to acheive varying degrees of fit. This technique was used this afternoon to lap the rotors on the Eta engines to just give that ideal clearance...
(https://lh4.googleusercontent.com/-ve476ujeOZg/UYqktQsoj3I/AAAAAAAAHu8/6SbufWklFis/s640/DSCF3034.JPG)

800 grit wet and dry used dry in this case. ( the gloves?  no not for allergy reasons but to cover up some pretty manky and inky fingers - been anodising this afternoon too and that's when I should have been wearing them  ::)

This method can be used in 'round' form too by wrapping some wet and dry around a mandrel - preferably plastic eg nylon to take out miniscule amounts - something else done this afternoon on a couple of the front bearing housings. Incidentally Jo if you don't want to go to the touble of making a lap this is what I would use for a small cylinder in brass/bronze such as your Crosskill providing the surface finish as bored is good to begin with - a quick 'polish' using 1200 W&D with paraffin as a lube will provide a very good surface with minimal pressure without affecting the bore consistency. As the piston can be made to fit and is probably best with a very small annular gap it's hardly worth the extra work involved.

We left off last time with a pic of the Bentley cylinder barrels and this is where the difference between lapping and honing was first experienced. Phil - 'pg100' has already alluded to in a very witty and most succinct way the merits of honing v lapping but I'd like to reinforce that with a couple of specific examples - one long ago and the other as recent as the other day (more on that later)

The Bentley design called for cast iron liners but at some 32.0 diameter all I could think of was the cost being turned into piles of swarf.
Exhibiting some of the early parts at a local show I met a well respected local engineer - Don Juler was well known for his prowess in making small racing motorcycles including the engines. I asked him what he thought I could make the liners from - Cast Iron came the instant reply - when I expressed my reluctance on cost he came up with a superb suggestion. You need some used valve guides from one of the local ship repairers - they throw loads away when overhauling engines. And so they did and so did I ;)

This is what's left after making those liners.  Centrifically cast and beautifully homogenous - absolutely superb to machine. The three upstanding bits are what the rings are to be made of - ah! but when  ::)
(https://lh6.googleusercontent.com/-siK7CcMRDWY/UYqr8Y42gGI/AAAAAAAAHvQ/SrVuTc5ygD4/s640/DSCF3038.JPG)

The liners were finished at 1mm wall thickness so the bores were done first and the OD's brought true by mounting them on an expanding mandrel - that way no distortion occurred of the thin wall. They were all bored to a plug gauge for consistency
(https://lh6.googleusercontent.com/-k8rxUPagP3U/UYExcgoGIvI/AAAAAAAAHi8/BX3TQatYnGc/s640/DSCF2733.JPG)

Turned from En1a and polished to a very smooth surface the lower gauge was the go-no go for turning and the top one was made for finishing - by honing - with a three stone cylinder hone. I had asked Don what he thought about Loctiting the liners in but he strongly advised a half thou or so press fit.  I don't know what my thinking was behind it at the time but it was certainly flawed you can see here the limit of the fit which does not go the length of the barrell - my first experience of fitting a liner to a barrel it turned out to be a real big mistake  ::)
(https://lh4.googleusercontent.com/-lOWHR4r9ORc/UYExfvKwq-I/AAAAAAAAHjE/EryJyzV7Lkc/s640/DSCF2737.JPG)

A piece of bar that already had a blind hole in it was pressed into use as a support for the liners and which would also act as a resevoir for the paraffin lubricant. The liners had tape wrapped around them to adapt to the bore....
(https://lh4.googleusercontent.com/-uHjxqQoVzT4/UYExTPjKJvI/AAAAAAAAHik/A-1t4oLxw80/s640/DSCF2728.JPG)

.... and the whole set up was ready to go
(https://lh4.googleusercontent.com/-Mqk6FQ4GYmc/UYExM3WPucI/AAAAAAAAHiU/ZUMgb8lMuag/s640/DSCF2724.JPG)

This was the limit set at the top stroke with the lower much the same but dipping in to the paraffin below.
(https://lh4.googleusercontent.com/-J_kQI_CLDcQ/UYExWBAeAvI/AAAAAAAAHis/OrS4ko-Qb04/s640/DSCF2729.JPG)

It was quite surprising how long it took to remove the small amount of metal for the gauge to go but the finish it produced was extremely good - very smooth but cross hatched. All the bores were treated so that the gauge would just slip through and they were ready for pressing into the liners. They pressed in lovely but oh dear, oh dearo bloody dear  :-[

The gauge would enter the lower bore but would not pass the point of interference fit - 'Golly Gosh' I think I said or was it something very similar.

I reset everything up to take out this aberation with the hone but it quickly became apparent there would be no control so a lap was made which quickly removed the tight area and the bore was restored albeit slightly larger allowing the no-go of the gauge to pass.

This is the lap - it's never been used since. The liners are two scrap that were out of tolerance
(https://lh3.googleusercontent.com/-LIYINrtFN9w/UYExoquHRYI/AAAAAAAAHjc/YXfYEpr0P7Y/s640/DSCF2755.JPG)

The liners were then honed to reproduce the cross hatching
(https://lh5.googleusercontent.com/-pDLyv1F1K0k/UYExlvkZk6I/AAAAAAAAHjU/eKnOesX-WcE/s640/DSCF2747.JPG)
and normal anxiety levels were quickly resumed ;)

I could see at this early stage that though the hones produce a very good finish they have no ability to true something up that for what ever reason may be well out. The lap on the other hand dealt with it swiftly and brought everything true again in quite short order.

This was the first real experience of the difference between the two and since then laps have been used for all I/C liners. The Waller engine on the other hand was quicly honed to take out the very small ridges left by machining. With an annular gap around the piston and a PTFE impregnated ring the seal is as good as could be wished for - for running on air.  As I mentioned before I have bought a bench mounted Delapena hone. Old but serviceable, it didn't cost much but as yet have no tooling - which does - to match the engine bores being made. As lapping appears to give as good a result as I currently require I'm beginning to see that as a bit of a white elephant  ::)

Personally I don't feel it's absolutely neccessary to lap a bore on every occasion eg a small engine run on air or steam unless it's out of true or tapered or the subject requires a piston/liner fit that has to be exceptional good - sized to fit pre- made rings for instance.

Hope that's not too long a post but I was trying to convey how it all began - bear with it - next time we'll get into making laps before dealing with the process itself  ;).


Regards for now - Ramon

Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Dan Rowe on May 08, 2013, 11:36:47 PM
I have a few valve guides that I brought home from the ships I worked on. If they were worn out of the limits listed in the book we just chucked them over the side. I wish I had grabbed a few more but I did get a few of the matching valves also worn beyond usable limits.

Very interesting.

Dan
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Don1966 on May 08, 2013, 11:53:29 PM
Very informate and well presented. I enjoyed this session of your class and await your next. Thank you Ramon.

Don
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 09, 2013, 02:25:56 AM
Excellent Ramon!.....Keep it coming!

 :praise2: :praise2: :praise2:

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: sco on May 09, 2013, 08:01:16 AM
Agreed - this is first class stuff!

We need a reference area to store this kind of thread.
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jo on May 09, 2013, 08:03:02 AM
Wow, a big

Thankyou  :ThumbsUp:.  


Looking forward to seeing more.

Jo
---
(One of the Guys  8))
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: swilliams on May 09, 2013, 08:32:53 AM
You've got my interest up Ramon. I'm looking forward to seeing more details about how you build your copper laps

Steve
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: pgp001 on May 09, 2013, 08:57:34 AM
Ramon

I wonder how much work would be involved in "making" the tooling for the Delapena.
My late dad had a full blown floor standing machine at one time, I have honed out a few sets of model radial engine cylinders on it for various friends, they do take some beating if you have the correct size tooling for them.

Excellent post on lapping by the way.

Phil
Title: Lapping (and honing) - some techniques for discussion
Post by: ths on May 09, 2013, 10:07:30 AM
Thanks Ramon, very informative, and I'm looking forward to the next class.

Hugh.
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: gbritnell on May 09, 2013, 12:29:34 PM
Hi Ramon,
Excellent tutorial on lapping. While I have lapped a lot of my engine cylinders with commercially made hones I have never tried making my own. Yours look to be quite simple and effective. Is there a chance we could get a sketch of the parts. I don't quite understand the shank being of the 'D bit' style and then the copper band being silver soldered to it.
Thanks,
gbritnell
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: b.lindsey on May 09, 2013, 02:53:12 PM
Nice intro to the topic Ramon, I am also looking forward to the next installment!

Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Bearcar1 on May 09, 2013, 04:12:23 PM
Hi Ramon, WOW! This is REALLY an interesting post and thank you for providing it to us. I can not wait to see how you went about making those industrial looking laps. I get the gist of them but am having a small problem envisioning their insides. I'll 'get it' when you show us the internals. This thread is going to be a real eye opener.  :o


BC1
Jim
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ian S C on May 09, 2013, 04:30:26 PM
I really must try a lap like yours Ramon, I'v been using wooden laps with variable results after hours of work.     Ian S C
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: ScroungerLee on May 09, 2013, 05:29:32 PM
Thanks Ramon for the thorough introduction, I am following along.  I too don't really understand what you meant about a d-bit being part of the tool.

Lee
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 09, 2013, 10:48:52 PM
Hi Guys - can't believe it - having spent some time going into the next bit I've just gone and lost the lot  :facepalm:
(I hit the back button - when you come back the box is empty  :o)

It's been a long day I guess and I'm just too tired to begin again - please bear with me - I'll get onto it tomorrow night - promise

Best laid plans an all that eh  ::)

Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 09, 2013, 11:12:00 PM
Happens to me too Ramon!....Sorry to hear man!
Tomorrow is another day.

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: ref1ection on May 09, 2013, 11:29:11 PM
There will be lots of us anxiously waiting for your next post.

Ray
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Bezalel on May 10, 2013, 04:45:02 AM
This is Great stuff Ramon
Thanks
 
I'm just lapping it up  ::)
 
 
If your still reading... let me tell you what I do for a long post. ( I've lost a few long posts myself in the past)
 
Just write your post in notepad/wordpad or some other plain text editor, take as long as you need to, even save it if you have to shut down the computer. Then when you're ready to post it Cut and past the text into the reply box, add a few smilies and hit the Post button.
 
Bez :cheers:
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 11, 2013, 09:48:31 PM
Hi guys - well we'll have another try - hopefully I won't hit the wrong 'key' tonight  ::) Thanks for the tip Bez but where the problem lies is moving back and forth getting pics from the web album - I just hit the back button by mistake.

I'd like to say how surprised I am in the interest in this subject - it's very pleasing to see but I can't reiterate enough that there are several ways of going about this - it's very much down to what suits the individual. That said I'm quite happy to continue - as said I hope it lives up to your expectations  :)

First off , my apologies Harry (GWR) - didn't mean to ignore you - I'm about 45 miles from Sudbury so if you're up around Beccles way and have some time to kill you'd be welcome to call. Theres also a very good stationary steam engine museum  about 9 miles south of Norwich - it'll be in steam first Sunday of June just in case you need a fix ;)

Okay back to the lapping  ;) -

If you discount the wet and dry wrapped around a smooth mandrel I guess the next best thing would be a hardwood dowel turned to fit a bore, split down the end with a screw to expand it. This provides an expandable lap but one of 'single point' form though agreed, as the lap wears, the land will widen. Providing the amount to come off really is minimal this would suffice to apply a better finish but not neccessarily keep the dimensions uniform down the length of the bore.

As you can see most of the laps made so far have been of one type. I think I first saw it in an article by Len Mason - a well known engine maker - but whoever it was the merits of it's consistency were praised. Having made that first one for the Quorn there's been no reason to change since until I did the last engines - the Super Tigres - when a differing kind was tried. This was successful too but nowhere as easy to operate as this kind.

I don't know how small they could be made as there is this need to silver solder a small controlled area but I would think about 3/8 / 10mm would be the limit without it becoming a technical challenge.

George  - I hope the following will be self explanatory without a sketch
So far they've been based around a 1/2" shaft - to fit a collet and if larger then a head is soldered on relative to the size required. The head is cut back like a D bit and a copper wrap is soldered to the leading edge. The cut off piece is inserted in the gap, A grubscrew locating it which is also used to expand it and the OD turned to about 1-2 thou / 0.025/0.05mm down on bore size.

The constituent parts
(https://lh3.googleusercontent.com/-fepKCShStj4/UYwUI-ZjGuI/AAAAAAAAHxU/6rj5kPQo8vQ/s640/DSCN3097.JPG)

The head is split and half cut away
(https://lh4.googleusercontent.com/-pWV0wFdvuzw/UYwULDoXBLI/AAAAAAAAHxc/8GMBIuZwu9s/s640/DSCN3099.JPG)

The wrap is annealed and formed around something to give the right diameter to fit the head - obviously the head has to be of such size as to leave sufficient for turning the od but not so big as once turned to leave little left for lapping. The wrap is drilled  clearance for the expanding screw, the fixed half is tapped for it and the insert is dimpled to act as a locater to stop it falling out.
(https://lh5.googleusercontent.com/-z51m-dZZgNQ/UYwUNsJq-SI/AAAAAAAAHxk/FeoxCB2x9lQ/s640/DSCN3101.JPG)

The inside leading edge is cleaned and the rest coated with a soft pencil - I believe Tippex makes a good resist for Silver Slder but haven't tried it and the same done to the head. Fluxed carefully on the cleaned areas the copper is held in place by a small screw through the copper and the edge soldered.
(https://lh4.googleusercontent.com/-V_Ldv0XAglU/UYwUQb8aQyI/AAAAAAAAHxs/ET51SECtu-0/s640/DSCN3105.JPG)

It's then set in the lathe and the OD turned, as said to a couple of thou max down on the bore - the abrasive has to have somewhere to go  ;)
(https://lh5.googleusercontent.com/-3DcHvFhF3og/UYwUS8C1McI/AAAAAAAAHx0/ycwcynA7lGI/s640/DSCN3109.JPG)

Bear in mind if you solder it to the wrong edge this is the op where you find out as it unwraps itself  :o - no it hasn't, not yet  :D

In use abrasive is mixed to a paste, applied to the lap and the part slid over - if it's too loose its witdrawn and the screw adjusted and tried until a good restriction is felt. Work the lap up and down to spread the abrasive then holding firmly set the lathe running at around 200 rpm slower is better to start with but not too slow. The part might grab at first but a good grip will soon have the two surfaces acting against each other as the abrasive begins to bite. I let the oil in the paste act as a lube for the first few seconds as the abrasive spreads out to an even film then I apply Paraffin (Kerosene) with some light lube oil mixed in (about 90-10) to keep things nice and wet. This is a messy process - I've tried using gloves but the loss of 'feel' and the problem of Nitrile gloves catching and winding up makes it much easier to get plenty of barrier cream on and volunteer to do all the washing up for a week  :D  It should go without saying but make sure the lathe ways are covered too.

Here are a few more pics of the same ops - this time it's the lap used for the first Eta engines being 're-wrapped' - the first time this has been done. Not quite as neat as the first time but successful never the less
(https://lh5.googleusercontent.com/-kZSIJ4wDUN8/UYgDDfFDHyI/AAAAAAAAHnY/aZtscBk7uA4/s640/DSCF2875.JPG)

(https://lh5.googleusercontent.com/-Pq8E2gESz9w/UYgDGRkjBhI/AAAAAAAAHng/YrdKY7k6u0Q/s640/DSCF2876.JPG)

(https://lh6.googleusercontent.com/-zYJL1X4E8TU/UYgDJVKcDPI/AAAAAAAAHno/vpzLILSj0Wo/s640/DSCF2883.JPG)

Despite the coating of graphite the solder has run a little further round than liked but none the less this worked well for all four cylinders
(https://lh4.googleusercontent.com/-umcn7kFc6yM/UYgDMjkN4iI/AAAAAAAAHnw/l2bc-VvkLdw/s640/DSCF2889.JPG)

The lap turned and coated with abrasive for the first lapping. The grade is 320 grit silicon carbide - we'll cover abrasive later
(https://lh6.googleusercontent.com/-9YE-sLxorHs/UYgDP3eiRtI/AAAAAAAAHn4/kjq8utd03IY/s640/DSCF2890.JPG)

The single point expansion gives a parallel lap at all times. I confess when I made that first one I could not see how it would remain round as it was gradually expanded but of course it is defined by the process - as mentioned before they gradually  become slightly eccentric to the shaft but retain perfect (within the remit of what they are) circularity. As the op is one of a floating nature the slight eccentricity has no effect on performance. I think it would be fair to say that to lap successful bores for  diesel engines goes some way to proving their viability.

I'd like to call it a day there - late night last night, early start this morning and a nice day sailing in the fresh air has finally caught up with me.

Regards for now - Ramon.

PS I see elsewhere Harry's preferrence not to have his post on his engine interupted. Without wishing to be seen as disagreeing with him, personally I would much prefer others to chip in/comment etc. To my way of thinking that way it's clear that the exercise is continually viable - I'm an inveterate worrier you see ;)
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 11, 2013, 11:02:14 PM
Outstanding write up Ramon!.....Can't wait to make one for the Wallaby
 :praise2: :praise2: :praise2:

We need lots of this.   This is good.   Thanks again

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Don1966 on May 11, 2013, 11:19:34 PM
I am loving it Ramon, a big thank you is in order. Great write up and presentation.  :praise2:  :praise2:

Don

Title: Re: Lapping (and honing) - some techniques for discussion
Post by: AussieJimG on May 12, 2013, 12:29:32 AM
Great explanation Ramon. One question: would soft solder be sufficient to hold the copper in place?

Jim
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Bearcar1 on May 12, 2013, 01:23:16 AM
I 'gots it' now, Ramon, and thank you for setting my feeble mind straight on the innards of these laps. They certainly are a huge step above the wooden laps that I have used in the past. Your tooling seems much more controllable and robust for the task at hand. Well done  :DrinkPint:


BC1
Jim
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: gbritnell on May 12, 2013, 02:28:05 AM
Ramon,
Thanks ever so much for the detailed explanation and photos. It now is perfectly clear. I just had trouble getting my head around the 'D' bit part of the explanation. Did you find that a certain thickness of copper worked better than another? I will be making some of these up shortly.
gbritnell
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: gbritnell on May 12, 2013, 02:34:36 AM
Ramon,
I have an idea that might work to prevent the excess solder from wicking back around the copper shell. How about cleaning up the copper and the lap, fluxing it up and using a piece of silver solder sheet material. Just cut a strip and lay it between the lap and the mandrel. Once everything is brought to heat there should only be enough silver solder to fuse the edge. It's a thought.
gbritnell
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: gary hart on May 12, 2013, 03:19:30 AM
Gbritnell,s idea sounds like a good one.   
 In my limited experiecne the best method of stopping solder going some place not wanted is a well oxidized surface.

Thinking if lap surface is oxidzed with a oxygen rich flame to badly discolored surface and then only the inner area of lap that want bonding is mechanically cleaned by sanding, filing or scrapping should keep silver solder going past the cleaned area.  Use a little more then minimum of flux and silver solder sheet as sugested by George.                     gary
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Bezalel on May 12, 2013, 04:19:41 AM
Great detail Ramon.
Thank you
 
I was thinking of the method of adhesion between the shaft and the copper, but Aussie beat me to it.
 
As I understand it the cylinder is hand held, so the forces involved must be relatively low and the temperatures produced during lapping must be well below the liquidus of eutectic Sn/Pb solder.  Or for that matter  any cyanoacrylate, adheasive. 
 
Are you aware of any reasons either method could not or should not be used? (other than that wasn't the way  the orignal was.)
 
Bez
 
 
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jo on May 12, 2013, 05:47:57 AM
Looks like I might need to make one of these for the Crosskill  :ThumbsUp:

Ramon you mentioned these work down to about 3/8",, the Crosskill is 7/16", what sort of problems do you get with these small laps? or is it more a case of making the lap?

Jo
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jasonb on May 12, 2013, 07:55:13 AM
George even using silver solder foil the solder will want to flow where the metal is clean so a resist is the best method, I tend to use Tipex (typewriter correction fluid) but must be the solvent based one.

Jo, I'd hang on until Ramon covers his more recent laps which would be easier to make in the small sizes.

J
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: modeng2000 on May 12, 2013, 07:57:13 AM
My thanks as well Raymon.

I would like to keep a paper copy of your writing and photos and wonder if there is a preferred way to do this. It would be just the relevant sections without the general comments, important as they are. Have tried copying and pasting to OpenOffice but not much success.

Perhaps you might be able to arrange your writings and photos as a pdf file or something like and then do an attachment.

Keep up the good work,
John
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jo on May 12, 2013, 08:15:50 AM
I'd hang on until Ramon covers his more recent laps which would be easier to make in the small sizes.

J

Will do, there is no rush for the Crosskill  :)

I wonder if lapping the cylinder is something I could use as part of the demonstration at the show  :thinking:

Jo
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 12, 2013, 11:19:06 AM
Wow - I didn't expect quite the response :o

George - at some stage in making these laps I used a piece of copper tube rather than making it from sheet. It soon transpired that the wall thickness was not really adequate from a 'lasting' point of view so since then I have used 10swg copper sheet and formed it by tapping around a form. This is about ideal - not so thick as to give too much resistance to the screw but plenty of meat left to use several times - even re-turning it to suit a smaller bore if required.

Re the solder question guys Georges idea is a good one - must admit I'd never given the thought to slipping  foil or even a piece of rod beaten to a flat section between the faces. It takes quite a bit of heat to get the steel up to temp with it surrounded by the copper so laying a piece of solder directly on the join line would not be so feasible as it would melt long before the work reached temperature.
I don't see why soft solder should not work either - just never tried it because as Bez remarks that was the original method. As a long time user of various cyanos in model aircraft I dont think the quality of join between the wrap and the steel would give a good enough joint for cyano to be an efficient substitute though - but you're right there is no heat in the process but there is at times considerable drag.

Jo - I don't know if you missed my previous answer in post 22 - just below the first pic -  but I think the work involved in making a lap like this might be a tad uneccessary - that said you may want to try but lapping brass would be another ball game using a copper lap, aluminium might be better and such a lap will get decribed later - tonight with luck  ;) Personally though, as said before, providing that your surface finish is good I'd just give it a quick smoothing with some 1200 wrapped round a smooth mandrel.

John ('modeng2002') - All the typing and images are done directly into the post box. Apart from the images none of it is kept on file so unfortunately what you see is all there is. I don't think I have time to help you here unfortunately - hope you understand.

I think that's covered everybody but if you've been 'missed' give me a dig

Regards for now - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: b.lindsey on May 12, 2013, 11:29:39 AM
Just wanted to add my thanks for the excellent write-up and pictures Ramon,,,very interesting thread to follow and am looking forward to more!

Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: tel on May 12, 2013, 11:42:55 AM
Same here - can't wait to give it a try! :ThumbsUp:
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: peatoluser on May 12, 2013, 02:13:07 PM
A superb tutorial. Picked up some really useful tips from your other posts Ramon, but for me, this is the icing on the cake! looking forward to the next instalment

peter
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Tennessee Whiskey on May 12, 2013, 02:34:32 PM
Ramon, if you ever want a couple of days " off" from here again we'll be glad to let you have them as long as you come back with this kinda stuff. Great tool, good design, easy to make, and maintain. :ThumbsU:ThumbsUp:     All request for time off should be directed to Zee, by the way :lolb:

Yo Redneck,
Eric
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Don1966 on May 12, 2013, 02:45:23 PM
Ramon I do have a question in regards to the length of the lap verses the length of the bore. I had read that the lap had to be 1/2 to 3/4 the length of the bore. Can you elaborate on this?

Don
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: zeeprogrammer on May 12, 2013, 02:51:19 PM
I was glad to see the post on how you made the lap Ramon. Very interesting. I learned a lot.

Good question Don.

Hush Eric.  ;D
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Bearcar1 on May 12, 2013, 03:43:10 PM
Keep those 'cards and letters' coming Ramon, this is proving to be a very stimulating subject and has many of us interested.  :ThumbsUp:


Bc1
Jim
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 13, 2013, 11:24:39 PM
Hi again 'guys' - time for a bit more ?

Couple of things first -

Don I have never given a great deal of thought to the actual length required - I don't actually know if there is a recommended length to diameter ratio.  Some of the commercial laps I've seen pics of seem to be quite long relative to their diameter but all the laps made so far have been around one and three quarters to twice the diameter. All the bores treated so far, though longer than the lap have responded well to this ratio without bell mouthing. They can also be used to lap a blind bore to within a small distance from the end.

Most of the small I/C engines dealt with  have had ''tapered' bores - that's in inverted commas because the degree of taper is not really measurable but more a 'feel' thing. This method of treating such a bore will get covered later but basically it's created by dwelling in the area required larger. It occurred to me after your query that possibly this type of lap could have a taper induced into it by providing a secondary screw in line with the first. Worth a thought perhaps.

On the last engines built a different form of lap was used - based on one made previously in aluminium and to all intents something that would open radially. A steel shaft was turned at a slow taper (5 degree inc.) and a D bit type tapered reamer made at the same time so that matching blanks could be made in the future. Incidentally using a more shallow taper makes for easier control but requires much more longitudinal movement for a give expansion. Too coarse and it will become extremely difficult to move using a reasonably small screw.
Although relatively easy to make it's 'shortcomings' soon transpired in that not only did it require considerable torque to expand but that once expanded it could not easily be released due to the slow taper.
(https://lh6.googleusercontent.com/-KhgE0DucjBg/T9uXLQzZi9I/AAAAAAAAGXU/AsNVA48gTCY/s640/DSCF0411.JPG)

On the Super Tigre build there was the requirement to lap the phosphor bronze bearing sleeves in the front and drum housings. These were relatively small bores 10.0 and 9.5mm diameter and aluminium was preferred because of lapping bronze...
(https://lh3.googleusercontent.com/-WXm5gDuDsKs/T9uXN8hgg0I/AAAAAAAAGXc/gaNirRXPpv8/s640/DSCF0415.JPG)

This time a mod was made - the shaft was reduced in diameter and a sleeve made to slide over it (front left) this way the collet and expanding screw could be slackened and the lap released by pushing on the screw using the tailstock. Not precise but it meant some control over over expansion

(https://lh4.googleusercontent.com/-1FpN8UgrMnI/T9uXP4SdaHI/AAAAAAAAGXk/ub-mgxGxy4A/s640/DSCF0418.JPG)

It worked extremely well however, lapping the bores to a very precise fit to accept their respective shafts - this is the front housing being lapped.
(https://lh5.googleusercontent.com/-6dJmvD5GaRE/T9uXRy961-I/AAAAAAAAGXs/96jN-O8F7PA/s640/DSCF0421.JPG)

When it came to doing the bores a larger lap was turned and this had radial grooves cut in to ease expansion - because these are not parallel to the taper but to the OD the amount of torque required to expand this was quite excessive.
(https://lh4.googleusercontent.com/-Hb-n1f4Quao/T-9iuCts5oI/AAAAAAAAGjU/6bacyNfSu4k/s640/DSCF0753.JPG)

Though a reasonably good finish was achieved it was felt that the aluminium did not give quite as good a finish on the En1a (12L14) as the copper laps do but comparatively it was quicker and perhaps easier to make. Personally however I would not go down this route again except in smaller sizes - say 10 mm and below. The control on expansion that the 'D bit' type lap gives is far far better.

I'm sure there are others who go about this in other ways - it would be good to hear from you if you do as there's always another way of doing something ;)

With the (internal) laps basically covered it's time to move on to the lapping itself. To do this a variety of grades of abrasive compound are required. There are several types of abrasive that can be used - Aluminium Oxide, Silicon Carbide, Diamond etc.
Except for the Diamond - which usually comes in paste form the difficulty is in getting these compounds in small amounts but there are sources to be found on the 'net. The use of the readily available diamond paste however is something to be treated with a degree of caution. It is really designed for lapping hardened steel components and as such it will embed itself in anything soft - lap and work - which will not come out with the usual solvent based methods of cleaning. To ensure all traces of compound are removed the work (and lap) require cleaning in an ultra-sonic cleaner. Obviously failure to remove particles of diamond compound will soon lead to the work lapping itself in further before probably lapping itself out again  ::)


Personal choice is Silicon Carbide - 'Carborundum' - but the variety does not have to be vast  - about three to four grades at the most. As with most things though it will depend on what's to be done - the material, amount to remove and the surface quality and/or any 'distortion'.
Valve grinding paste can be used at a push thought the coarsest is probably too coarse for the kind of work likely to be encountered. I have no idea what the actually grades are but I would think that the 'coarse' is much coarser than 320 grit which is about ideal for the initial lapping of steel/cast iron.

These small jars contain Silicon Carbide powder mixed with a small amount of light oil to a thin and runny, paste like constituency
(https://lh4.googleusercontent.com/-vcQz4s8M7f8/T-9iyNQAJfI/AAAAAAAAGjk/DxXhgCrGo_E/s640/DSCF0766.JPG)

The three larger jars contain cellulose (gun cleaner thinner) The part is popped into each in turn to clean it - After an initial wipe with paper towel a good swirl in the first to remove the worst followed by the next two in turn produces a pretty clean part ready for checking.

To give some idea of the effectiveness these two cylinders are after the initial lapping with the ali lap above using 320 grit - the one on the right still showing traces of tool marks requiring just another 'lick'
(https://lh6.googleusercontent.com/-NL4LLR1XShg/T-9i0EkqeyI/AAAAAAAAGjs/Vhp5HOLkuwk/s640/DSCF0768.JPG)

Hope that's enough for tonight - just had that late night usual 'reminder' "Bathroom's free''  ;)

Next we'll get to grips with the lapping process itself.

Regards for now - Ramon



Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Don1966 on May 14, 2013, 01:01:02 AM
Ramon, thanks for your response to my question. I have again enjoyed your very informative class and look forward to more. Again thank you very much for taking of your time to give us these lessons.

Don
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: pgp001 on May 14, 2013, 06:52:48 AM
Nice one Ramon, excellent write up.

Where do you get your lapping grit from by the way, I assume it is no different to blasting media.
I have access to around 100 tons of various grades of the stuff at work, so no problem there.

Phil
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jo on May 14, 2013, 07:21:17 AM
Oh nice. Ramon those look really useful. Which would you recommend for the Crosskill which has a 7/16" bore? the Aluminium or the copper? And where do you buy your Silicon Carbide powder for doing the lapping?

Thanks again Ramon, these posts are really useful  :ThumbsUp:.

Jo
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: sco on May 14, 2013, 07:27:29 AM
G H Thomas talks about using 'horological powder' for lapping dovetails.

Simon.
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: capin on May 15, 2013, 12:17:05 AM
 :) Mr Ramon, thanks for sharing your knowledge and mastery of the trades with us ! I as so many here wait daily for the class lesson. Thanks again, Brian
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: swilliams on May 15, 2013, 02:11:58 PM
Great stuff Ramon

I've got to make one of those D-bit type copper laps, they look the business.

Steve
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: tangler on May 15, 2013, 02:21:25 PM
Lapidary suppliers seem to supply small quantities of SiC powder.  I've just remembered that we have a small stone tumbler in the loft - I must go and investigate, it could be useful for all sorts of model engineering stuff!

Thanks to Ramon for taking the trouble to expound on his techniques.

cheers,
Rod
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 15, 2013, 05:31:37 PM
Hi guys - thanks as usual  :ThumbsUp:

I was intending to carry on with a some more tonight but had overlooked the fact that it's 'change of cap' time - Plastic Model Group meeting tonight  ;)

If I'm back in reasonable time maybe but failing that tomorrow for sure.

Have checked out the lapidiary suppliers since the last post - just be aware that they supply powders at the very coarse end - F320 grit is about the coarsest that's needed for our use.

Regards - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: gbritnell on May 15, 2013, 07:55:38 PM
Hi Ramon,
Plastic models too! I started building plastic when I was about 9 and still do to this day. Our club meets once a month. We have auctions, shows, contests and just plain bull sessions. I just finished an F-86 Sabre decked out in the Canadian show team colors of the Sky Lancers.
gbritnell
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: pgp001 on May 15, 2013, 08:39:00 PM
I used to think blokes who were into making plastic models were not "real" model engineers.

That is until I saw one of Ramons early posts showing the jet fighter he has built and detailed, now I consider myself to be a reasonably competent model engineer, but I honestly could not see myself managing to do anything like that.

It deserves a second look
http://www.modelenginemaker.com/index.php/topic,1344.msg17986.html#msg17986

Phil
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 16, 2013, 09:30:22 PM
Hi Guy's - a good night last night but a bit too late back ;)

First off a digression OT

George - I'm pleased to hear that you too enjoy the plastic world along with others on here. I returned to it about ten years ago when I made a model of a Lancaster for my cousin in law's eigthieth birthday. It was the time of the build up to the Gulf War and having made military models in the early seventies couldn't help but think what ideal subjects some of the armour would make festooned as they were with all kinds of kit. 'Fate?' decreed seeing a Tamiya magazine for the first time which had a stunning feature on a Russian T55 tank all heavily weathered - I was hooked  ;)

Phil - Thanks for your kind comment but personally, though I often use lathe or mill to create parts, I don't consider plastic modelling 'model engineering' either. It is however IMHO a true modelling form in it's own right. Gone are the days when all there was was 'Airfix' - today the hobby has an unbelievably vast amount to offer for anyones creativity and some of the results are just simply outstanding. With todays modern machining methods however the tooling that produces these incredibly shaped plastic parts must be something truly special to see.

Forgive the digression - back to the laps ;)


One of the first things done even if it's a one off is to turn up a accurate plug gauge about 0.005mm down on required bore diameter. Given the fact that most have very limited means to accurately measure a bore using a plug gauge will not only get you very close to the limits required but will give you a very good idea of whats 'going on' inside the bore - high spots or taper are soon detected if the fit is good.  Usually made (for me) from En1a (12L14) and polished to a high degree the only thing to be wary of in a liner made from similar steel is galling or 'pick up' The bore must be thoroughly cleaned of any trace of lapping compound before trying.
(https://lh3.googleusercontent.com/-VSwmrlG1xTI/UYgC8bdlMHI/AAAAAAAAHnI/O9AjtbAFYrM/s640/DSCF2860.JPG)

(https://lh3.googleusercontent.com/-669-waa6hfA/UYgC5J5iypI/AAAAAAAAHnA/stAV-QOAIHI/s640/DSCF2851.JPG)

A note before we go further - this is a very messy process.  I have tried using gloves but the lack of feel with work gloves is quickly noticeable, Nitrile gloves on the other hand constantly get nipped between lap and part and get ripped if you're lucky and wind round the lap if you're not  :o Theres only one thing for it - lots of barrier cream and reluctantly accept to offer to do the dishes for a week ::)  I think I've said this somewhere before but it's worth repeating

The lap should be set such that the liner hits the chuck when about 25-30% of the lap protrudes - any more and bell mouthing can begin to occur. A card or plywood, plastic or fibre washer is place over the shaft to prevent the liner galling on the chuck jaws as can be seen below. The limit of travel at the other end can either be by a matter of judgement or a stop can be set in the toolpost. One made from a piece of 6mm ply works well.

The premixed 320 grit compound then is wiped over the lap with a finger ...
(https://lh6.googleusercontent.com/-9YE-sLxorHs/UYgDP3eiRtI/AAAAAAAAHn4/kjq8utd03IY/s640/DSCF2890.JPG)

With the lathe stationary, the liner is pushed on and the paste worked about. The liner should not be forced on - the grit will offer a resistance and this is something that must be learnt - it wants to be a tightish fit without excessive force but if it is loose then remove and expand the lap a little. Obviously if too tight then wipe a fair amount of the grit off and try again. If the lap was made with the clearance as recommended then there's probably too much compound.  Taking a good grip on the liner the lathe is set running at about 200 rpm and the liner immediately moved back and forth to spread the paste uniformly throughout the liner and lap.
Stop at this point and apply plenty of lubricant. It should look like this... (note this is withdrawn this far for the pic !)
(https://lh6.googleusercontent.com/-I5UWIxV3NHY/UYgDcaTAfoI/AAAAAAAAHoY/lw1fca4rAvs/s640/DSCF2910.JPG)

Paraffin (kerosene) with a small amount of oil (about 90:10) is an ideal lubricant but others may prefer to use something else.
(https://lh5.googleusercontent.com/-gHHOwBK9Jrc/UYgDfb0zKPI/AAAAAAAAHog/flFr7jpUkSY/s640/DSCF2915.JPG)

This is the kind of wetness ...
(https://lh3.googleusercontent.com/-WIhl5vHBh_k/UYgDip4QOAI/AAAAAAAAHoo/dU6P73bqScg/s640/DSCF2920.JPG)

The liner is moved back and forth reasonably quickly - not excessively - until the lap goes loose. Sometimes more lubricant has the effect of re-arranging the grit which gives a bit more lapping resistance but eventually - in a reasonably short space of time the lap is obviously no longer working. Clean up and check the bore using the plug gauge then if required repeat the process, expanding the lap a little further. Continue this until the gauge feels as if it will just enter.

The following  pics give a better idea of the amount of protrusion of the lap. Although a slightly tapered bore is beneficial in these small diesel engines, at this stage the aim is to produce a parallel bore with a smooth matt finish devoid of all tool marks - preferably throughout the bore but particularly above the exhaust line.
(https://lh3.googleusercontent.com/-KpJCgGUBFkA/UYgDTOUmodI/AAAAAAAAHoA/75sobY4XbRg/s640/DSCF2901.JPG)

(https://lh3.googleusercontent.com/-egwZreMTKos/UYgDWfClsrI/AAAAAAAAHoI/A0WYpkCoHjU/s640/DSCF2904.JPG)

(https://lh6.googleusercontent.com/-gQqTFGvdBzY/UYgDZvl7FWI/AAAAAAAAHoQ/J420NqAJUPM/s640/DSCF2905.JPG)

Everything should be 'smoothing out' by now and the lap should look like this
(https://lh4.googleusercontent.com/-2A_QNbHdVuQ/UYlO0iPU_7I/AAAAAAAAHpc/QAlQ1VCGWeY/s640/DSCF2958.JPG)

Unfortunately this is not a good pic but the liners require a nice uniform matt finish at this stage with the plug gauge just able to enter - on no account should it be forced if tight but if it does get stuck tap it out gently from the other side using a short piece of wood as a drift. Obviously if the bore should get scored doing this the only option is to lap it further to remove the scoring.
(https://lh3.googleusercontent.com/-rNP9erocudA/UYlOxWgMptI/AAAAAAAAHpU/2Qn7GqGvVTA/s640/DSCF2948.JPG)

If this was a steam engine bore personally I would leave it at this stage. If there was the desire to cross hatch it this would be the point to use a cylinder hone. I have no experience of fitting piston rings as yet but this is the stage I would leave a bore if I was - as shown before, the Bentley liners are such.

Model aircraft 'Diesels' on the other hand require a much better piston and liner fit to obtain the compression seal required and further work is required to bring the liner to that stage - more on that next time.

I'm trying to keep the momentum up on this so my apologies for any 'gaps'.  However as mentioned a while back there's the need to get this article finished for Model Engineer - guess what stage we're up to on that today  ::) Sues on holiday this week coming too so that may just have a bearing  ;)

Bear with it  ;)

Regards for now - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 16, 2013, 09:40:03 PM
Ya doin fine man!

Keep it coming Ramon!   this is good!

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Don1966 on May 17, 2013, 12:56:45 AM
Another great lesson, just keep it coming Ramon. I really appreciate your efforts and time. Thanks again.

Don
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jasonb on May 17, 2013, 07:40:08 AM
Quote
turn up a accurate plug gauge about 0.005 down on required bore diameter

Just for any of out US friends it may be worth pointing out thats 0.005mm not 0.005"  :facepalm:
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 17, 2013, 08:32:58 AM
Well spotted Jason - glad to see the text is read too  ;)

I try to ensure all measurements are noted as metric as that's what I work in most of the time only refering to imperial where necessary - this one slipped the net but you have to agree the 'pic' was in metric.. ;D
(https://lh3.googleusercontent.com/-VSwmrlG1xTI/UYgC8bdlMHI/AAAAAAAAHnI/O9AjtbAFYrM/s640/DSCF2860.JPG)

I'll modify the post - thanks

Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: b.lindsey on May 17, 2013, 12:56:33 PM
Ramon, just a question...from the pictures it is obvious that both the cylinder as wall as the lap itself are being abraded away albeit slowly...hence the matte finish on both surfaces.  I am curious if you have ever done any measurements on how much the copper diameter changes and if a harder cylinder material (say steel or cast iron as opposed to brass) tends to wear the copper away at a faster rate? Certainly the diameter of the copper part can be increased as needed both to take up for abrasion to the copper and to achieve the desired cylinder bore and I understand that, i am just wondering if there is any feel for the relative amounts of abrasion to the lap and the cylinder and how that changes based on cylinder material?  Hope that makes some sense.

Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 17, 2013, 01:26:15 PM
Hi Bill, that's a good question. I assume you are meaning the amount the copper wears relative to it's use - the actual diameter varies very little,  the annular gap getting smaller as the grit size diminishes.

If it's wear have to admit I don't know - I've never ever thought to see how much the lap actually loses, I guess by being totally focussed on the liner bore measurement. The lap is just expanded as required. I do 'measure' it occasionally as used to keep tabs on any out of roundness - which so far has not been found - but not in reference to it's actual thickness/wear. Never really given it a thought before  ::) I haven't used 'copper in brass' so can't say but in cast iron and En1a (12L14) the wear appears about the same - in high tensile steel a little more. As you might expect the real wear comes in the initial lapping to remove the tool marks - it's surprising how little is required to refine the finish after that unless inducing a taper which takes a little more time.

I would say these are very much 'make and use' tools - they are not suited for sustained runs or long term continuous use - depending on the turned finish in bore to begin with I would say 6-10 bores would be a good average in mild steel.

Hope that helps some - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: b.lindsey on May 17, 2013, 01:34:07 PM
Thanks Ramon...that does help!

Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 17, 2013, 10:41:34 PM
You're welcome Bill  :)

Following on from the previous post the technique used to create the conditions for a good piston/liner seal in a compression ignition model engine - usually mis-referred to as a 'diesel' is fundamentally more of the same but using a finer grit - in this case F600 - to smooth out the bore and induce a very slow taper from the bottom of the liner to just about where Top Dead Centre would be preferably slightly lower than higher. Technically it isn't neccessary to produce a taper at all but by doing so it provides a the means to lap the piston exactly to the dimension required and also once finished and in place reduces friction in the lower part of the bore. The taper is very small dimensionaly - certainly not measurable with basic kit but again the plug gauge will give an indication.

The lap is thoroughly cleaned of all traces of the 320 grit and a similar paste mixed using F600. The procedure is exactly as with the 320 but this time the lap is allowed to dwell at the bottom end and the lap is not taken all the way up the cylinder. Ideally the area taken up by the contra piston should remain as previously lapped but allowing the lap to go through this area every so often will not affect this too much - certainly not enough to cause concern. It does not take long to produce a situation where the plug gauge, with everything nice and clean, will now enter the bottom of the bore with ease but beginning to tighten at around the exhaust position. As soon as this state is reached any further lapping is really to 'polish'. Lots of lubricant but no more paste. just expanding the lap to provide a slight contact if it gets too loose.

Previously a further lapping using F1000 powder has been carried out but on this latest batch it was felt that the finish acheived with 600 was sufficient for the next stage which is to lap the piston to the bore. The resultant seals are just as good if not slightly better than previous.
These are the liners done for the Racers  - the first of the scaled up engines as you can see the 1000 gives a high degree of polish
(https://lh3.googleusercontent.com/-_anWPQhwZXE/S9dYnJtHPvI/AAAAAAAAFiw/1RmuKETgNiM/s640/DSCN2331.JPG)
on the left is cast iron the right is high tensile steel which appears to polish to a higher finish than En1a

These are the two Tigre liners as shown previously having been lapped with 600 - very smooth but no sheen.
(https://lh3.googleusercontent.com/-w94qmJQLMkw/T-9i65JQ-eI/AAAAAAAAGj8/9zrSNSNlzV8/s640/DSCF0779.JPG)


Before the piston can be lapped to a perfect fit with the liner the piston itself requires lapping. For this an external lap requires making. Whilst all that was available was a home made lap something that was considered to be very desirable was an external hone. After along wait for the right kind I was finally able to secure two sets at very reasonable cost off E-Bay. Much to my surprise when they arrived they were absolutely untouched - just one, easily replaced, screw missing
(https://lh6.googleusercontent.com/-2mQXGA2CO1U/T9er5uxklEI/AAAAAAAAGV4/N8QrDKjXQ5k/s640/DSCF0360.JPG)

Desirable yes but not exactly neccessary - Used on the Tigre engines they do work well but appear to have no advantage at all over this....
(https://lh6.googleusercontent.com/-nEDGt81_T84/UYwUYC7BSOI/AAAAAAAAHyE/3mJszmJEs2s/s640/DSCN3115.JPG)

Easily made, this piston lap works extremely well and removes metal just as easily as the hone - the hones were left in the box on this latest batch - the lap you see has done all seven Etas and the original gap cut to allow closing just short of nipping up on the last piston

The procedure is the same  for the liner - begining with 320 the piston is coated and a smear applied to the lap
(https://lh4.googleusercontent.com/-FD90gRKWERE/UYlO6xCDgBI/AAAAAAAAHps/G70vcbqQJgI/s640/DSCF2975.JPG)

Constantly checking the dimension, the diameter is reduced until the top of the piston will just enter the bore by about 3mm or so then the lap is cleaned and the grit changed to 600.
(https://lh4.googleusercontent.com/-Bzmak0NgRbc/UYlO9_LHbuI/AAAAAAAAHp0/bQwnUK0ye9c/s640/DSCF2979.JPG)

The lapping continues until the piston will enter the lower bore becoming tight as the crown reaches just below the exhaust area. Lapping on the lathe stops at this point and the remaining lapping of piston to liner is carried out by hand
(https://lh6.googleusercontent.com/-RaCdbQ1rD1c/UYlmRNk0C5I/AAAAAAAAHtc/1aJeRhb2gLY/s640/DSCF2991.JPG)

Once again the piston and liner is thoroughly cleaned of all traces of the previous compound. A tee handle driver is required and this has an end that will fit inside the piston with a cross hole that will take a reasonably tight fitting brass 'wrist pin'
(https://lh5.googleusercontent.com/-qiTfFzpABYU/T_HRJgXhMJI/AAAAAAAAGlk/omcChyB19ZE/s640/DSCF0810.JPG)

The piston is attached to the end of the rod and a very small amount of F1000 compound previously mixed applied to the piston and smeared around
(https://lh4.googleusercontent.com/-wAHeqqlIDzk/UYlPVWQ9dFI/AAAAAAAAHq0/ADXwsIe01DI/s640/DSCF3007.JPG)

The piston is then inserted into the liner and with a very slow wringing and in and out action the piston/liner are gradually lapped together.
(https://lh5.googleusercontent.com/-KJahryb1muc/T_HRNtb5UZI/AAAAAAAAGl0/N7QIJ_9An_4/s640/DSCF0819.JPG)

By it's very nature this is a slow process and one that cannot be rushed if a good result is to be achieved. If the piston begins to tighten and stick it shouldn't be forced - it can tend to pull itself in - tapping it gently from the other end using a wooden dowel or similar as a driver will soon release it. Wipe some of the paste off and apply plenty of lube and continue. This op does not require much compound. It  can take as much as 15-20 mins for this op - but once the piston is fully inside and about halfway up the bore past the exhaust it's removed and wiped clean - no more - and relubed.
(https://lh6.googleusercontent.com/-cxLEYYWfXkw/T_HRWlxK7lI/AAAAAAAAGmY/YE4Wp4iv40Q/s640/DSCF0829.JPG)

All the lapping from this point uses the residual compound and lots of lube. When it begins to squeak it's getting dry so it's removed, more lube applied and the process continued
(https://lh3.googleusercontent.com/-NZrUBLFmPfg/T_HRUtufPmI/AAAAAAAAGmQ/rPnoITh4vYs/s640/DSCF0826.JPG)

The piston is lapped in this fashion until the skirt is just level with the bottom of the exhaust....
(https://lh3.googleusercontent.com/-YdizX_xHVro/UYlPPhUru2I/AAAAAAAAHqk/hlj4ToZZLus/s640/DSCF2996.JPG)

... then removed and thoroughly cleaned in solvent. If an ultrasonic cleaner is available then a quick rinse in that is ideal after cleaning.

That's enough for tonight - sailing day tomorrow   :) and an early start

regards - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 22, 2013, 08:35:08 PM
Hi again 'Guys'  - apologies for the delay but family problems got in the way. I think we should be able to bring my input on this to a close tonight - hopefully others will add their experiences to the pot  ;)

Once the piston is lapped to the liner it should be removed and stored safely awaiting assembly. The contra piston can now be tackled. Like the prop driver this small item can be a bit awkward to hold to get all the ops done - Previously I have bored the back (top face) out to a strong push fit on an expanding mandrel with the screw removed. The spring in the mandrel providing the drive. This has proved more than sufficient grip to turn the outer diameter and to turn in any concavity required as well as for the lapping.

This can be carried out using the piston lap but the fit required is finely toleranced - too tight and the comp screw is hard to turn and the contra piston difficult to 'fire' back up the liner if over compressed. Too loose and the feel on the screw is marginal at best and the comp screw can easily back off when running though this can of course be compensated for by a locking bar. The lap however is much wider than the CP and can induce 'barrelling' by wringing easily.

After trying several methods however I have settled on using two fine flat india stones held by hand which gives excellent control, is easily rendered and stock removal is quickly judged......

(https://lh6.googleusercontent.com/-sp228jl7mxg/T_NLM1JrYQI/AAAAAAAAGnU/7TOXuzsi9BI/s640/DSCF0869.JPG)

(https://lh6.googleusercontent.com/-WhKN7IFmNNg/UYlPYe4bEpI/AAAAAAAAHq8/hOFX4lckQ3E/s640/DSCF3009.JPG)

(https://lh5.googleusercontent.com/-OobrrB5nq8A/UYlPbaDKquI/AAAAAAAAHrE/g4kWeqjN_2Y/s640/DSCF3010.JPG)

As you can see the two stones are nipped gently together at the lower end holding them in contact at the top end with slight fingure pressure. With the lathe running the stones are moved in a slight arc back and forth across the CP pivoting the stones in the lower fingers. With plenty of lube this gives very good surface finish with no loss of roundness (A single stone can soon induce that BTW) and as said good dimensional control though constant measuring is the order of the day. It needs to be a tight but easy (if that makes sense) push fit in the liner. It's better to be tighter - more can come off, but looser - well the solution to that has already been covered on the Eta build  ;)

A couple of follow up things that should be of interest ....

You may recall the query that kicked this all of was the difference between lapping and using sprung arm cylinder hones to 'true' a bore.
You may also recall that when the cylinder fins were shrunk onto the liner for the Mk2 Elite that they weren't quite in line. Well, in my haste to try to put that right I quickly set the liner in the soft jaws gripping on the exhaust flange in the hope that I might get sufficient leverage to twist the fins slightly. What I didn't notice was that the part of the jaws behind the cut out gripping the flange was just - fractionally just - too small and consequently distorted the liner below the exhaust flange. First thought was that it was a 'bin-ner' but on measuring the distortion appeared to be only about 0.04mm and had not affected the bore above the flange. Lapping took this anomaly out without any difficulties and produced a nice round lower bore albeit slightly larger than that planned.  I took this pic to try to show the distortion accentuated by the lapping. Though not that brilliant you can however just see an un-lapped area (horizontal tool marks) between the two matt areas directly below the top most cut out.
(https://lh5.googleusercontent.com/-2CPE9dw-5I4/UYgDmc2rK0I/AAAAAAAAHow/Bg1aQAmdJ1E/s640/DSCF2924.JPG)

I think it would be fair to say this would never have come out with a sprung loaded hone.
The piston lapped to the bore as well as the others and the engine appears at the first running to have a distinct 'edge' to the others. Less friction at the bottom end? who knows.


The other small thing of interest was something tried for the first time. When the second Elite was assembled it was obvious the piston had not lapped itself in quite far enough up the bore, the piston becoming very tight about 10 degrees before TDC. I was about to re-lap with a very tiny amount of F1000 but remembered that I had been given some 'Diamontine' - at least that's what I think it's called. Despite it's name I'm pretty sure it's not actually a diamond based product however it's a very fine white powder. I had not tried it before so decided to give it a go.

It quickly lapped the high spot out and in so doing  produced an exceptionally polished surface at the tight spot
(https://lh4.googleusercontent.com/-tev85Gs4V9E/UY1JO6J70qI/AAAAAAAAHyc/ZE6VPwnMYdc/s640/DSCF3074.JPG)
Again not a very good image but you can see the top band around the piston and the shiner part in the bore. Pleasingly the piston seal on this engine is the best yet.


Well Guy's I think that's about as far as my input can go on this subject. I'm positive there's more to come however so please add to it.

Thank you all for your encouraging words on the way which as always have been much appreciated. I have enjoyed doing it and it should go without saying but if just one bore get's improved it will make it all worthwhile  :).

Regards - Ramon

Title: Re: Lapping (and honing) - some techniques for discussion
Post by: tangler on May 22, 2013, 10:28:48 PM
Ramon,

Thank you very much indeed.  Very instructive.  You've clearly developed a successful technique and I, for one, have learned a lot.

Cheers,

Rod
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: b.lindsey on May 23, 2013, 12:33:41 AM
Ramon, I know how much time this took to put together and write up with the great photos and such. Thanks for doing this, I also learned a lot and appreciate all your effort in putting it together in such a clear and instructive way.

Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Maryak on May 23, 2013, 12:42:32 AM
Ramon, I know how much time this took to put together and write up with the great photos and such. Thanks for doing this, I also learned a lot and appreciate all your effort in putting it together in such a clear and instructive way.

Bill

Me 2, Thanks Ramon  :NotWorthy:

Best Regards
Bob
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Don1966 on May 23, 2013, 01:50:10 AM
Thank you again Ramon for you time and efforts. I have learned a lot about lapping and believe me I knew very little when you started. It is good to have such knowledge posted here for all of us to learn from. I await your next lesson with great interest.

Don
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: bp on May 23, 2013, 01:59:31 AM
Terrific stuff Ramon.  Lapping/honing has always been a bit of a black art.  You have illuminated the darkness!!
cheers
Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 23, 2013, 02:05:37 AM
Thanks Ramon!....per our discussion, I'll be lapping the bore and quill on my SB 9   Tailstock.   It is slightly different because of bore depth...but I'll tell ya...you have set the standard for the subject...and I'll be hard pressed to do the subject any justice at all!

 :NotWorthy: :praise2: :NotWorthy: :praise2:
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: AussieJimG on May 23, 2013, 06:04:58 AM
Thank you Ramon, I could not put it better than Bill has already done.

I can't help feeling that lots of us will be doing a bit more lapping and getting better results.

Jim
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: vcutajar on May 23, 2013, 07:03:41 AM
Thanks Ramon for a very instructive thread.

Vince
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jo on May 23, 2013, 07:15:36 AM
Thanks Ramon that was excellent   :AllHailTheKing:

Jo
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: mhirst121 on May 23, 2013, 09:50:53 AM
Thank you very much for taking the time to do this Ramon, it really has opened my eyes to the art of lapping.

MartinH
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: ozzie46 on May 23, 2013, 12:04:05 PM

  Thanks very much Ramon. Very instructive and very much appreciated. As I am making my first IC engine this will come in very handy indeed.

  Ron
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: cfellows on May 23, 2013, 03:36:49 PM
Thanks for the effort you put into this, Ramon.  Very helpful.

Chuck
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 23, 2013, 10:51:14 PM
Hi 'Guys'
A quick word to say thank you for all your words of thanks and kind comments. It's really pleasing to think that this has proved useful and has been of interest to you.

I'd just like to say that I see it as nothing more than passing on the information imparted to me either by dear old Len Evans in the first place or by reading about the laps - probably another Len, Len Mason and of course the writings of my own 'engine guru' American George Aldrich. By sharing the the experience gained by following these people is just following on behind them.

I have begun work on a 2.5cc S&J version but after that is finished I shall be taking a break - another distraction is heading my way I'm afraid ;)

Thanks again everybody - your comments are much appreciated

regards - Ramon
Title: Lapping (and honing) - some techniques for discussion
Post by: ths on May 23, 2013, 11:54:19 PM
My thanks as well, Ramon, echoing what has already been said.

Do the moderators feel that perhaps a techniques section could be opened? There is much that could go into it apart from this post, and digging around to find it in the bar stock engine section, that may not be easily remembered, could be frustrating. Bogs has also reposted articles that could find a home there. I realise that most build posts have aspects of technique in them, but this one is a fairly is a fairly pure example.

Cheers, Hugh.
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 24, 2013, 01:59:29 AM
Excellent point Hugh....I think it would fit just fine in the Hints, tips and Tricks section....If there aren't any objections by morning or so I'll move it over there tomorrow.

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Alan Haisley on May 24, 2013, 02:58:07 AM
Dave,
It certainly belongs there. This is a fine piece of work that can help anyone building a model.
Thanks, Ramon.
Alan
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 24, 2013, 03:11:18 AM
OK

It's moved.   Ramon...if you object, let me know and back it goes

Where ever you want it is alright by me.

 :praise2:

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Stuart on May 24, 2013, 07:19:08 AM
To Steamer

What I am suggesting could only be done with Ramon's permission

could the post done by Ramon be extracted and place in a thread on its own and made a sticky as a technical how to that as Hugh suggested be able to be found by us and any new members


may be another child board to hold such threads when they have run there course , But i do think that the entire thread be left intact as a tribute to Ramon for his hard work in putting this valuable information together


Stuart
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: modeng2000 on May 24, 2013, 07:28:13 AM
To Steamer

What I am suggesting could only be done with Ramon's permission

could the post done by Ramon be extracted and place in a thread on its own and made a sticky as a technical how to that as Hugh suggested be able to be found by us and any new members.

Stuart

That is an excellent idea.

John
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 24, 2013, 10:10:10 AM
Hi 'Guys'

I had thought when posting last night that that might be the end of things so it was a pleasant surprise to see your comments this morning  :)

Having read them a while ago and thought about the matter over breakfast perhaps I can offer an opinion and suggestion.

First off - Dave - I have no objection to you having moved the thread however I'm still not so sure it's quite the right place. You may recall that at the outset I didn't feel there was anywhere really 'specific' to place such a thread so stuck to where I was posting about the Eta's - and that probably isn't the right place either  ::)

On that note then I do feel that perhaps considerstion should be given to creating a new board such as 'Workshop Techniques' for threads such as this Lapping one.
 
As opposed to small 'tips' or 'wrinkles' in the Board for such, threads in the new one would be expected, by their nature, to not only cover a subject in detail but also be open for discussion at all times even after the main coverage has ended. It should perhaps also remain (if that is possible) as Stuart has suggested a 'Sticky'. This would prevent any thread disappearing with the passage of time into the backlog of threads but still allow further relevant input or updates.

I have previously had work 'published' as 'Tutorials' on the Barton Control Line Forum but have to say feel uneasy with this in that no input is allowed - I can see the reasoning but the lack of potential of relevant questions being asked as the thread progresses, albeit there is the opportunity to do so on another discussion thread seems to make the whole thing - for me - somewhat dictatorial. As a community there should be the means for all to make comment - future readers have the choice, to skip the comments or be aware of how well (or not) it's recieved.

So that's my suggestion -

That a new Board is created for 'Workshop Methods/Techniques

It could cover such matters as Screw-Cutting, Heat Treatment, Painting, Casting, Ignition Systems, Anodising to name but a few - there is a lot of experience out there that could be tapped into - and then kept at the forefront on our Forum for the benefit of new members.

I would add however that having said all that I'm quite happy for the status quo to remain too - it's just a thought  :)

Regards to all - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 24, 2013, 10:22:02 AM
All

I'll look into doing this.  Thanks for the input...thats what makes this a nice place!

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 24, 2013, 05:36:04 PM
Hey Ramon,

How thick is the copper that you made the lap out of?

Looks about say 3mm or 1/8"....

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 24, 2013, 05:44:45 PM
Hi Dave - yes that's about right - actually 10swg copper sheet. Without checking I think that's 128 thou so you're close enough  ;)

Ramon

Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 24, 2013, 06:24:29 PM
Thanks Ramon!...I'll probably make an expansion lap like your aluminum ones....all I got stock for ! :lolb:


Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Mosey on May 24, 2013, 10:16:33 PM
Not wanting to sound stupid, but is there anything to be said for using "Timesaver" lapping compounds? They seem to work well for this rookie. Perhaps, they go well with the laps you are making?
Mosey
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 24, 2013, 11:18:19 PM
Hi Mosey, no you're not sounding stupid - apparently 'Timesaver' compounds are just fine. Over here though they tend to be on the expensive side due to the minimum amount that can be bought - makes it a pricey outlay for the odd cylinder.

After reading about it I did look into getting some but the cost/quantity put me off so have not used it however I have seen very favourable reports on its capabilities - I believe it has the properties of still giving good cutting qualities as it breaks down under the process - in effect giving a finer grit - would that be correct?

Regards - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: AussieJimG on May 25, 2013, 01:01:10 AM
As I understand it, Timesaver is based on Feldspar which continues to break down to a fine, non-abrasive powder so it ultimately stops cutting. Compare this with other abrasives that will keep cutting if they are not scrupulously removed from the work.

I assume that the time saved is the time otherwise spent cleaning the work.

The cleaner Bon Ami is also based on Feldspar (later formulations also contain Calcium Carbonate in the form of limestone). Some old time engine builders would throw a bit of Bon Ami into the air intake of a running engine to help bed in the rings.

Jim
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Maryak on May 25, 2013, 02:15:02 AM
The cleaner Bon Ami is also based on Feldspar (later formulations also contain Calcium Carbonate in the form of limestone). Some old time engine builders would throw a bit of Bon Ami into the air intake of a running engine to help bed in the rings.

Jim

This old timer's done it more than once. ;D

Best Regards
Bob
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Mosey on May 25, 2013, 02:54:06 AM
I've purchased 2 small jars of Timesaver, one for alum and one for ferrous metals and tried them out. They are super easy, and yes they just stop cutting as you want. They were reasonable in cost, I think about $20.00 for the 2. In the past I used diamond paste and valve grinding paste. Don't care for either for the usual reasons.
Try to find these sample size jars that are not too costly. I did my pistons with Timesaver, alum in cast iron.
Mosey
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 25, 2013, 08:41:34 AM
Thanks for the explanation and putting me right here Jim

I have just checked the 'Timesaver' site here in the UK and it's 41 a 1lb tin of each grade. They do a four grade kit of 3oz tins at 81. I guess theres 20% VAT to add to that so that makes it a mite expensive to me.

To me Silicon Carbide breaks down just as well but does leave a residue which if not cleaned properly will continue to abrade. Cleaning as described in cellulose thinner is quick, easy and very effective. As I see it you would still have to clean using Timesaver
before checking size and/or fitting the piston so nothing much would be gained - taking into account the cost differential.

As also said diamond will embed itself into any thing other than hardened material which only a clean in an ultra sonic cleaner will remove. When used at work diamond lapping was done on a different lapping surface to that of Carborundum. I cant remember the name of it but a special material in sheet form was stuck to a flat surface for use as a diamond lapping surface.

I'm off sailing now but will pop a couple of pics up tonight.

Regards - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Jasonb on May 25, 2013, 09:02:56 AM
One of the most cost effective ways to set yourself up with a range of lapping powders is to go for one of the sets or a selected range of grits from a good woodworking suppliers where they are used to true sharpening stones and also flatten plane soles.

In the US any Lee Vally (http://www.leevalley.com/US/wood/page.aspx?p=33017&cat=1,43072) stockist should be able to get them or use the web. In the UK they are available from Axminster Power Tools (http://www.axminster.co.uk/veritas-veritas-lapping-powder-(2oz)-prod822760/) or Brimarc (http://www.brimarc.com/search/results?query=lapping&index%5B%5D=all&submit=Search) stockist , In Europe some where likeDieter Schmid's Fine Tools (http://www.fine-tools.com/abrichtblock.html#ziel109025) would be a good place to try.

J
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: b.lindsey on May 25, 2013, 11:45:23 AM
Ramon, the Timesaver folks have a website here in the US also and show the 4 grade sample kits at a reasonable price, but I notice that the grades range from 40 to 320 on the green (for steels and cast irons). You had indicated I think that 320 is about the coarsest needed for model work. So where are you finding the finer grades?

Bill
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 25, 2013, 02:47:49 PM
Ramon,

When we spoke last, I mentioned watching  Rollie Gaucher give a talk at NEMES about making laps...well I'm in luck
They video taped the presentation (2008)

Here's a link.....interesting talk it was!

And some of the laps Rollie uses....( His Bently BR2 is exquisit)

Dave



http://neme-s.org/2008_February_Meeting/nemes_monthly_meeting.htm

Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 25, 2013, 02:49:13 PM
Gadget builders comments and use can be found here.

http://www.gadgetbuilder.com/Lapping.html


Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Mosey on May 25, 2013, 04:33:28 PM
You can purchase "Timesaver" lapping compounds from; WS2coating.com at One 3oz jar of the grit of your choice for $9.00, or a test kit of Eight jars, one of each grit for $60.00

It is made with Silica and Barium Sulphate.

I have used them successfully, and have no interest in the product or company. They work well for rookies like me. :ThumbsUp:

Mosey
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Dan Rowe on May 25, 2013, 08:25:22 PM
On the ships I worked we always had several grades of Clover Brand lapping paste. The usual jobs ranged from lapping globe valves made of steel or brass to flat lapping air compressor valves on a flat plate. Diesel engines have several metal to metal high pressure fits that are maintained by lapping. Usually there is a special lap that comes with the engine to maintain the surface but sometimes a special lap has to be made.

Here is one I made from scrap for a special case.
(http://i586.photobucket.com/albums/ss307/shayloco/MEM/Lapper-web_zpsdb73334a.jpg) (http://s586.photobucket.com/user/shayloco/media/MEM/Lapper-web_zpsdb73334a.jpg.html)

I needed to lap down a small hole for a combustion gas pressure fit. Lapping was easy but cleaning in the hole not as simple. The usual process was clean rags and Electroclean for final cleaning.

We had a fancy kit to sharpen special copper laps for Sulzer fuel injector nozzles which we used 1200 grit Clover paste. Man was that a tedious process which had to be kept very clean.

I still use Clover Brand lapping past in my shop as I have had a bit of experience with it.

Ramon many thanks for posting your detailed experience.

Dan
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: steamer on May 25, 2013, 08:51:27 PM
I use Clover also Dan!

Dave
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Ramon on May 25, 2013, 11:44:22 PM
Ramon, the Timesaver folks have a website here in the US also and show the 4 grade sample kits at a reasonable price, but I notice that the grades range from 40 to 320 on the green (for steels and cast irons). You had indicated I think that 320 is about the coarsest needed for model work. So where are you finding the finer grades?

Bill

Hi Bill et al - I'm not certain if the grading nomclemature is uniform across various abrasive products - diamond for instance is certainly different from the silicon carbide 'Carborundum' that I use. I have found on the bores done so far that 320 is about the coarsest need to begin the process, even with (relatively) quite deep tool marks. I have some at F240 but this appears to be too excessive for the sizes involved and can quickly score the laps leading to galling or 'pick up'.

Cost of the 'Timesaver' in the States is a big improvement from over here so unless some 'comes my way' I think it unlikely I will part with the cash as I have plenty of silicon carbide to last.

I mentioned the material we used to use for flat lapping - still can't recall the name but here's a couple of pics..

First off though is the usual grooved cast iron lapping plate used for conventional abrasives - a bit on the thick side, I've often thought it's a bit of a waste - there might be a flywheel lurking in that blank  ;)
(https://lh5.googleusercontent.com/-5cKT3FR_iFk/UaE1CGJ71zI/AAAAAAAAH3A/jTs5xAnJBh0/s640/DSCF3162.JPG)

The plate used purely for diamond abrasive - one side coarse the other fine. It comes with a self adhesive backing and is specifically designed for the task. It was mainly used on carbide tooling parts but also hardened steel components too. This is from work, the block of steel is bolster plate ground flat  - I don't think it's ever been used at home.
(https://lh6.googleusercontent.com/-28n8muuZVM8/UaEYJtUKa_I/AAAAAAAAH2w/R22XHOOmsZc/s640/DSCF3158.JPG)

A close up of the surface - despite being a 'stick on' product it's very flat and uniform.
(https://lh6.googleusercontent.com/-53a3r96iP8A/UaE1FJ5MfRI/AAAAAAAAH3I/2euTIKDqCLg/s640/DSCF3169.JPG)

Yesterday I turned the backplate for this small engine currently being worked on. The rear drum housing had an 8.00mm hole bored in rather than reamed and the surface finished with some 1200 wet and dry simply wrapped around a wooden dowel. Carefull application with plenty of paraffin lube soon had this 'lapped' to a running fit for an 8mm dowel pin used as a plug gauge the drum itself turned from tool steel lapped down to a easy running fit. So far so good but its got to be H&T'd yet - distortion could prove a problem as yet.

Regards - Ramon
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Maryak on May 25, 2013, 11:59:59 PM
On the ships I worked we always had several grades of Clover Brand lapping paste. The usual jobs ranged from lapping globe valves made of steel or brass to flat lapping air compressor valves on a flat plate.
Dan

Yep, good old Clover but you forgot Brasso and Bon Ami/Vim and toothpaste ;D

Best Regards
Bob
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: ScroungerLee on May 26, 2013, 05:00:22 PM
Also Soft Scrub cleaner which is a very fine abrasive.  I wonder if it breaks down?

Lee
Title: Re: Lapping (and honing) - some techniques for discussion
Post by: Laurentic on June 15, 2017, 10:38:52 PM
Yes, I know it's four years down the line from the last post, but I just wanted to thank Ramon for describing in detail his lapping/honing device. 

I have just made one, to suit a cylinder of 0.7875" bore, and it worked a treat, I could not believe how well it performed, went from a finish that compared with a ploughed field to a nicely hatched and very smooth cylinder bore - delighted, using just 'coarse' and 'fine' grinding paste (as used by motor mechanics everywhere) and finished with cutting oil and then finally 'Brasso'.  Cannot (at the moment) see any reason to try anything else.........

Chris
 :DrinkPint: