Author Topic: Floating Reamer Holders  (Read 12645 times)

Offline Roger B

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Floating Reamer Holders
« on: November 03, 2016, 11:27:55 AM »
I am aware of the need for floating reamer holders to get the best possible accuracy and finish when reaming in the lathe. Industrial ones are too big and will probably cost more than my lathe. Hemingway offer a kit:

http://www.hemingwaykits.com/acatalog/Floating_Reamer_Holder.html

This is also too big for me  :( By the time I have fitted a chuck and a reamer I have almost no space left for a workpiece  ::)

The working principle is to offer a small amount of axial and angular freedom whilst transmitting torque. Most available units seem to use something like an Oldham coupling to transmit the torque and some form of thrust ball.

As the amount of torque required when reaming is quite low (or should be) I am looking at a different principle. To keep the unit short the floating Morse taper will not be full length, the remaining part of the chuck or reamer taper will be inside the taper of the tailstock quill. The floating action will be by two pairs of links at 90° connected by a ring that fits around the floating Morse taper. One pair of links will fix to an adaptor that clamps to the outside of the tailstock quill, the other pair will be attached to the floating Morse taper. There will be a small clearance (~0.25mm) between the floating Morse taper and the ring and adaptor to limit the movements. The links will pivot on hardened steel bushes held in place with M3 caphead screws.

Will this work? I can see a few potential problems  :headscratch:

1) The links will tend to twist with the torque. Close tolerances should reduce this.
2) Will the weight of the chuck tend to deflect small reamers, exchanging one problem for another? By small I am thinking of the ~1.5mm reamers used for my injection system.
3) The torque reaction on the links will tend to withdraw the reamer, possibly starting a chatter problem.

All thoughts, ideas and suggestions welcome  :ThumbsUp: :ThumbsUp:  :wine1:
« Last Edit: November 03, 2016, 11:59:41 AM by Roger B »
Best regards

Roger

Offline Admiral_dk

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Re: Floating Reamer Holders
« Reply #1 on: November 03, 2016, 08:50:57 PM »
Hi Roger

A very interesting problem. My first thought before opening your drawing was a coupling like the ones on my CNC router between the steppers and the shafts. One of these might support a micro chuck and could potentially do what you need in the very small sizes.

The cheap and cheerful :
http://www.banggood.com/5mm-x-6_35mm-Aluminum-Flexible-Shaft-Coupling-OD19mm-x-L25mm-CNC-Stepper-Motor-Coupler-Connector-p-993600.html

The really good quality :
http://www.lovejoy-inc.com/products/disc-coupling.aspx

And the in between quality :
http://www.cncrouterparts.com/oldham-zero-backlash-couplers-p-223.html

I really should think about one for myself too  :old:

Offline Lew Hartswick

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Re: Floating Reamer Holders
« Reply #2 on: November 04, 2016, 02:28:09 PM »
I've been curious about this "device/concept" for a long time. The above links to the "idea" in the OP is beyond me. Is there a description to be found somewhere on how the principal works. In a bit more detail than what has been said above. ????
   Thanks.
   ...lew...

Online Jo

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Re: Floating Reamer Holders
« Reply #3 on: November 04, 2016, 03:26:33 PM »
This is a commercial one.  Taking it apart there are three main parts:

1, The bit that mounts in the tailstock has a slot in it for using a morse taper extractor in and note the dome screws line up with that slot.
2, The interesting floating/fixed middle bit - more later  ;)
3, The floating bit the tool mounts in which has the morse taper socket in it and you will notice the mounting screws are at 90 degrees to the slot on the morse taper for extracting.

The clever bit is that middle bit  :naughty:: The floating bit the tool mounts in is clamped to the first outer ring by two allen screws. At 90 degrees to those screws on the ring is two pins that allow the central tube to move left and right. To the other end of the central tube: is another outer ring with two pins at 90 degrees to the first pair. this give the up and down movement. That ring is clamped by the two domed head screws to the first part. So if you put all three bits together you get two movement axes left/right and up/down.

Now it gets posh: the central part also has a big spring round the outside of the tube and a plate. The plate screws on the front of the bit that goes in the tailstock using three csk screws and is the surface that the floating tool holder floats on. The spring lives behind this plate and pulls the tube and the attached floating tool holder back against the surface.

The result is you have a morse taper socket that is free to move in two planes while maintaining its parallelism with the axis of the mounting taper.

I hope that is clear as mud  :headscratch:

Jo

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Offline Roger B

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Re: Floating Reamer Holders
« Reply #4 on: November 04, 2016, 03:35:32 PM »
The idea, as I have understood it, is that a reamer will follow an existing hole opening it out accurately to size and leaving a good surface finish. If the reamer cannot follow the existing hole, for example if the tailstock of the lathe is not very accurately aligned with the headstock the side pressure on the reamer will cause the hole to be tapered/bellmouthed, the tendency to cut on one side of the reamer only will cause chatter and the surface finish will be degraded.

The question is how accurate must the alignment be? I think that the answer must be better than the tolerance expected in the hole after reaming.

The floating reamer holder is supposed to allow the reamer a small amount of freedom to follow the existing hole and to transmit the cutting torque. How much freedom is required? Again I think that the answer must be more than the inaccuracy of the headstock-tailstock alignment. Typically this will be a couple of degrees angular and a couple of tenths of a mm axially.

I hope that this clarifies things a little  :headscratch: I am certainly not a machining specialist, but this is what I have found from various books and websites.
Best regards

Roger

Offline Roger B

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Re: Floating Reamer Holders
« Reply #5 on: November 04, 2016, 03:38:46 PM »
Thank you for the pictures Jo  :ThumbsUp:

How big is that one, MT2? Who was/is the supplier?
Best regards

Roger

Online Jo

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Re: Floating Reamer Holders
« Reply #6 on: November 04, 2016, 04:09:58 PM »
You are welcome Roger,

That is a Clarkson floating reamer holder. Currently fitted with a 2MT but by the looks of things the socket in the end can be replace by other sizes.

As for the supplier: It turned up at my model engineering club at our white elephant sale and I think I was the only person who put a bid on it  ::)

Jo
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Offline Lew Hartswick

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Re: Floating Reamer Holders
« Reply #7 on: November 05, 2016, 02:03:43 AM »
This is a commercial one.  Taking it apart there are three main parts:

I hope that is clear as mud  :headscratch:

Jo

Thank you. That helps  a lot. The angular "float" is not quite clear yet but I'll work on it. :-)
   ...lew...

Offline Roger B

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Re: Floating Reamer Holders
« Reply #8 on: November 06, 2016, 07:26:55 AM »
This is the 'Swiss' version. An MT1 - ER11 version exists. I may pluck up courage to ask how much  ::)

The description of operation and the diagrams are good. Looking at Jo's version and this one I think that I would need to add some centering springs between the floating Morse taper and the tailstock quill on my design.
Best regards

Roger

Offline Roger B

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Re: Floating Reamer Holders
« Reply #9 on: November 08, 2016, 07:34:08 AM »
The MT1-ER11 Angst floating reamer will cost me CHF 700  :o Actually it is not as bad as I thought it might be  ::)

Now I have 3 options so I need to decide how much my workshop time is worth:

1) Continue my own design with uncretain success. Cheap but will consume quite a few hours.
2) Use the Hemingway design as a basis but shrink it a bit. Costs a bit more but should work. Will also consume quite a few hours.
3) Spends lots of money and spend the workshop time building engines.

 :headscratch:  :headscratch:
Best regards

Roger

Online Jo

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Re: Floating Reamer Holders
« Reply #10 on: November 08, 2016, 07:45:54 AM »
3a) Buy some model engine castings  :naughty:

A copy of the Clarkson floating reamer would not be difficult to make  ;)

Jo
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Offline Rivergypsy

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Re: Floating Reamer Holders
« Reply #11 on: November 08, 2016, 01:20:20 PM »
An interesting problem, and one I've spent more than a few hours on to try to 'float' a leadscrew, so that the rotary motion doesn't affect the linear travel (long story), but what I stumbled across was a flexure based system what allows float in 4 degree of freedom, but is rigid in the two required - perhaps this could be modified to float a reamer?

Offline cwelkie

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Re: Floating Reamer Holders
« Reply #12 on: November 08, 2016, 01:35:26 PM »
FWIW here are some photos of a holder I put together a while back. Sorry, no drawings. It uses interchangeable "heads" so I can use it for different size dies and taps.







Hopefully the photos are self-explanatory.
Charlie




Offline kvom

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Re: Floating Reamer Holders
« Reply #13 on: November 08, 2016, 03:30:24 PM »
Nothing I build would benefit from whatever advantages such a holder could offer.  Interesting discussion however.

Offline gerritv

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Re: Floating Reamer Holders
« Reply #14 on: November 08, 2016, 05:20:07 PM »
Charlie, that is a very neat Implementation.
Don't confuse activity with progress

Offline Roger B

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Re: Floating Reamer Holders
« Reply #15 on: November 08, 2016, 05:27:05 PM »
Charlie, A nice tool  :ThumbsUp:  :ThumbsUp: , have you tried it with small reamers? What size is the taper?
Best regards

Roger

Offline Tennessee Whiskey

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Re: Floating Reamer Holders
« Reply #16 on: November 08, 2016, 07:29:23 PM »
I think Chuck Fellows purchased a floating reamer holder from one of our gunsmith supply houses on this side of the pond,  perhaps you have an equivalent.

Cletus

Offline Roger B

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Re: Floating Reamer Holders
« Reply #17 on: November 08, 2016, 08:33:20 PM »
Thank you Cletus  :ThumbsUp:

I had a search on some gunsmiths suppliers. In the UK guns are pretty well a no go area, in mainland Europe it's a bit easier. There is a Swiss branch of a US supplier which offers a Manson floating reamer holder. It looks a bit bigger than I need and would require an MT 1 shank to be made. I will look further into Manson Precision.

http://www.brownells.ch/epages/Switzerland.sf/de_CH/?ObjectID=55053
Best regards

Roger

Offline cwelkie

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Re: Floating Reamer Holders
« Reply #18 on: November 09, 2016, 02:49:36 AM »
Thanks for the kind comments.
Roger - it's an MT3 taper.  Just used a "blank-head" arbor as a starting point.
Cheers
Cw

Online Chipswitheverything

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Re: Floating Reamer Holders
« Reply #19 on: November 09, 2016, 09:20:18 AM »
Interesting discussion and very helpful photos of the various tooling items.
 But Roger, if you are mostly wanting to use a floating holder on the very small diameter , c.  1.5mm reamers that you indicate, will the reamers have any stiffness sufficient to exert a centering action upon the spring loaded and perhaps fairly stiff action of the typical floating holders?  I do wonder if a reamer of, maybe, 4mm or more is needed before this happens.
 Don't know what machinery you are using, but Is the alignment of your lathe headstock to tailstock actually far enough out to concern you when reaming small sizes?  Or could you make some improvement to the alignment, check the tailstock set over carefully for instance?  Another idea that occurs is to make a little holding bush for the reamer shank, held in the tailstock, (in chuck or better, directly in the taper ), and drilled and reamed (!) in situ from the headstock.  If it was a taper shank, it could be marked to be re-align able for subsequent removal and re insertion...   Dave

Offline Roger B

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Re: Floating Reamer Holders
« Reply #20 on: November 09, 2016, 11:17:34 AM »
Thank you Dave  :ThumbsUp:

The answer to most of it is I don't know but am trying to learn  :headscratch:  :headscratch:

My lathe is a Hobbymat with a D shaped bed so there is no easy way to adjust the tailstock. I don't think that it is too far out for general use, but from what I understand when reaming the alignment should be better than the tolerance you are expecting, hence the need for floating holders.

There appears to be several types of floating holder, some just allow for axial misalignment like Jo's Clarkson and the Manson unit from the gunsmith website. Other versions also compensate for angular misalignment in various ways.

Do I need to compensate for angular misalignment? I don't know, but as I am drilling some quite deep small holes, 2mm dia 20mm deep, it is quite likely that the drill will wander.

Most of the holders are obviously too big and heavy for my requirements. The small sized ones I have found do specify a range, typically 1-7mm diameter reamers often using ER11 collets so I have to assume that the spring tension range (adjustable on some units) is appropriate for these sizes.

This is certainly an interesting learning experience and once again I thank everyone for their support and interest.
« Last Edit: November 10, 2016, 07:00:45 PM by Roger B »
Best regards

Roger

Offline Dan Rowe

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Re: Floating Reamer Holders
« Reply #21 on: November 09, 2016, 02:20:31 PM »
Roger,
I have been following this topic with interest. I do not have any answers just learning like you. I found a floating holder that has spring pressure adjustment for both types of misalignment with a drawing and explanation of use.
http://batzberg-manufaktur.ch/documents/Floating%20Reamer%20Holder.pdf

Dan
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Offline engjas

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Re: Floating Reamer Holders
« Reply #22 on: November 10, 2016, 09:48:43 AM »
Hello Roger
I too have been interested in this topic sufficiently so to have spent a few pleasurable moments looking up old patents for such devices. Several are variations on what I recognise as the "oldham" coupling, others use rubber as the flexible element along with springs, some of the more simpler devices utilise spring loaded spherical elements. All very interesting. Have a look on Google Patents.

However the pragmatist in me wonders if you are attempting to solve a problem that might not exist or possibly not as bad as you would believe. Have you actually tried to ream your 2.0 mm by 20 deep hole and measured the result? Could you measure (detect) any error?

From the patents information it might be possible, but I've not tried, to grip a 2mm reamer inside a rubber tube (say something like bunsen burner gas tube) inside a tailstock (Jacobs) chuck sufficiently to cut but yet be flexible enough to float a little.

Some times a change of approach can also give better results. For instance if concentricity is a real issue or exact location then is it possible to put the hole in first and then manufacture the outside to suit? I recall an article years ago by Professor Denis chaddock titled putting the cart before the hores wherein he outlined machining of a crankcase for an IC engine from a cube staring with all the important holes and whittling the outside to shape llater.

Sorry not to have any real answers just my two pence (cents)worth.

Good luck and please let us all know how you get on.

John

Offline Roger B

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Re: Floating Reamer Holders
« Reply #23 on: November 10, 2016, 11:42:46 AM »
Thank you Dan  :ThumbsUp: Batzberg produce the Angst floating holder I mentioned earlier. Their MT1-ER11 unit would suit admirably except for the price  :(

John, I am not quite sure how real the problem is  :headscratch: This relates to my fuel injection system experiments:

http://www.modelenginemaker.com/index.php/topic,4906.0.html

I have already made a number of trial pieces by drilling, reaming and lapping. The better the finish and accuracy after reaming is the better chance I have of reaching my (sub?) micron target. For the injection pump position and concentricity are not critical, just the quality of the bore. For the injector itself the bore needs to be concentric with the nozzle hole but I have resolved this by using the bore to guide the nozzle drill and seat cutter.

I think that a floating reamer holder will help, but I need to invest either significant workshop time or money to find out  ::) There is very little information available on how others have solved this problem.

Best regards

Roger

Offline Dan Rowe

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Re: Floating Reamer Holders
« Reply #24 on: November 10, 2016, 03:48:21 PM »
Roger,
Now that you have explained what you are trying to accomplish have you considered ballizing? A funny word for pressing a precise carbide ball in a slightly undersized hole.
http://nationalballomatic.com/basics.php

I have not tried this but I found it interesting and low cost.

Dan
ShaylocoDan

Offline Roger B

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Re: Floating Reamer Holders
« Reply #25 on: November 10, 2016, 05:42:07 PM »
Thank you again Dan  :ThumbsUp: I am aware of 'ballizing'. It was mentioned on here a couple of years ago when Hobbynut was having problems with the injection system for his Lister 6/1:

http://www.modelenginemaker.com/index.php/topic,1742.225.html

I don't know how he got on, but it seemed to me that the hole had to be extremely straight and true before this technique would work. I ended up with one banana shaped bore where the pin gauge would enter more than halfway from both ends but would not go through  ::)
Best regards

Roger

Offline Roger B

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Re: Floating Reamer Holders
« Reply #26 on: November 12, 2016, 06:24:06 PM »
I have an injection pump body that I had reamed but not yet lapped. It was drilled 1.7mm then reamed 1.95mm. I have a 1.97mm pin gauge that will go into that starting end 4 or 5mm and a couple of mm into the leaving end. The 1.98 mm pin gauge will just enter the starting end so there is from my viewpoint significant bellmouthing. The target after lapping is 1.98mm (2mm silver steel hardened and then lapped).
The picture is of a previously lapped pump body. It's from 10mm square bar stock.
Best regards

Roger

Offline Roger B

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Re: Floating Reamer Holders
« Reply #27 on: March 22, 2017, 07:48:30 PM »
I had another go at this. The tailstock on my Hobbymat is split so the sleeve can be clamped. I had made another pump body and this time for reaming I tightened the clamp as far as possible to reduce any movement of the tailstock chuck.
The result was that after reaming 1.95mm the 1.97mm pin gauge passed straight through and the 1.98mm gauge would enter significantly from both ends. This was worse that leaving the clamp loose.
I think that I need to spend some money on a floating reamer holder  :headscratch:
Best regards

Roger

Offline Roger B

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Re: Floating Reamer Holders
« Reply #28 on: April 23, 2017, 07:40:16 PM »
I finally decided to buy an Angst floating reamer holder. The MT1 version was no longer available so I got one with a 14mm dia 25mm long stub and a soft end MT1 arbour.

The arbour was bored out to fit and then I tried some experiments. I used the same 10mm square black bar that I use for the pumps and injectors, but without spending time on the offset turning.

For the first trial I center drilled quite deep, set the side centering force to minimum and left the pendulum adjustment in the middle. The hole was drilled 1.8 mm at 2000rpm and them reamed 1.95mm at 500rpm (same for all trials).

In this case the 1.97 pin gauge would not enter from the exit end but went in around 4mm from the entry end.

I tried again with a smaller center drilling and got similar results. I then tried with a smaller drill chuck (3mm max) to reduce the overhang and adjusted the pendulum resistance to maximum. This was worse, the 1.97 pin gauge would enter around 6mm and I could feel a jolt as the reamer entered.

I them adjusted the pendulum resistance to absolute minimum (last thread on the screw) and tried again. This time the 1.97 pin gauge would enter less than 2mm.

There is definitely something in this  :headscratch: Is the floating holder worth it? I think it may be if I am doing a lot of injector work, but I need a few more pin gauges to confirm.

As ever the bores can be corrected by lapping, but the better the bores are to start with the quicker you will reach a good finish.
Best regards

Roger

Offline Admiral_dk

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Re: Floating Reamer Holders
« Reply #29 on: April 23, 2017, 09:45:48 PM »
We continue to wish that you will succeed with your endeavour - but I must admit, that I'm not sure if you end up with a recommendation or not .....

Offline Roger B

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Re: Floating Reamer Holders
« Reply #30 on: July 01, 2017, 03:29:09 PM »
I got back on this again as I need to get on with the fuel pump and injector for the two stroke diesel. I looked up the manufacturers site for the Magafor reamers I am using. The figures for a 2mm reamer suggest ~2400rpm and a feed of 0.1 - 0.15 mm per rev. My lathe can achieve 2000 rpm and has fine feeds of 0.08 and 0.16 mm per rev. I decided on 0.08mm per rev. I also purchased new Titex drills in 1.8, 1.85 and 1.9 mm diameters. For these trials I didn't power feed the reamer but just followed the carriage by eye. The feed was much slower than I have been using previously.
All trials used the same 1.95mm H7 reamer

1st Trial
Center drill without countersink. 1.85mm dia. drill. Reamer held in a normal chuck.
1.96mm pin gauge passes through
1.97mm pin gauge enters ~5mm from the start end and ~2 mm from the exit end.
1.98mm pin gauge enters ~2mm from the start end

2nd Trial
As above but using the floating reamer holder. The reamer was difficult to start in the hole.
1.96mm pin gauge passes through
1.97mm pin gauge enters ~2mm from the start end but not from the exit end
1.98mm pin gauge no go

3rd Trial
As above but with a countersink from the center drill.
1.96mm pin gauge passes through
1.97mm pin gauge enters ~1mm from the start end but not from the exit end
1.98mm pin gauge no go

4th Trial
As above but 1.8mm drill. More force was required to feed the reamer.
1.96mm pin gauge passes through
1.97mm pin gauge enters ~3mm from the start end but not from the exit end
1.98mm pin gauge enters ~1mm from the start end

5th Trial
As above but 1.9mm drill.
The hole was over 1.95mm so the reamer passed through without cutting.

Conclusion:
Following the manufacturers recommendations helps. The floating reamer holder greatly reduces bell mouthing.


« Last Edit: July 01, 2017, 07:50:38 PM by Roger B »
Best regards

Roger

Offline Admiral_dk

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Re: Floating Reamer Holders
« Reply #31 on: July 01, 2017, 08:35:56 PM »
Nice to see that you are moving forward  :ThumbsUp:

 

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