Author Topic: Lapping (and honing) - some techniques for discussion  (Read 51400 times)

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Re: Lapping (and honing) - some techniques for discussion
« Reply #105 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
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Offline Mosey

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Re: Lapping (and honing) - some techniques for discussion
« Reply #106 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

Offline Ramon

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Re: Lapping (and honing) - some techniques for discussion
« Reply #107 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
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Offline AussieJimG

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Re: Lapping (and honing) - some techniques for discussion
« Reply #108 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

Offline Maryak

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Re: Lapping (and honing) - some techniques for discussion
« Reply #109 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
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline Mosey

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Re: Lapping (and honing) - some techniques for discussion
« Reply #110 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

Offline Ramon

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Re: Lapping (and honing) - some techniques for discussion
« Reply #111 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
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Offline Jasonb

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Re: Lapping (and honing) - some techniques for discussion
« Reply #112 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 stockist should be able to get them or use the web. In the UK they are available from Axminster Power Tools or Brimarc stockist , In Europe some where likeDieter Schmid's Fine Tools would be a good place to try.

J

Offline b.lindsey

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Re: Lapping (and honing) - some techniques for discussion
« Reply #113 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
« Last Edit: May 25, 2013, 08:40:11 PM by b.lindsey »

Online steamer

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Re: Lapping (and honing) - some techniques for discussion
« Reply #114 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

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Online steamer

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Re: Lapping (and honing) - some techniques for discussion
« Reply #115 on: May 25, 2013, 02:49:13 PM »
Gadget builders comments and use can be found here.

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


Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Mosey

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Re: Lapping (and honing) - some techniques for discussion
« Reply #116 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

Offline Dan Rowe

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Re: Lapping (and honing) - some techniques for discussion
« Reply #117 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.


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
ShaylocoDan

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Re: Lapping (and honing) - some techniques for discussion
« Reply #118 on: May 25, 2013, 08:51:27 PM »
I use Clover also Dan!

Dave
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Offline Ramon

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Re: Lapping (and honing) - some techniques for discussion
« Reply #119 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  ;)


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.


A close up of the surface - despite being a 'stick on' product it's very flat and uniform.


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
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)