# Floating reamer experiment



## Rob Thule (Apr 20, 2022)

I flirted with the idea of making a floating reamer holder in order to compensate for any misalignment in the lathe and mill.

I came across a design by Bill Zweig (https://www.practicalmachinist.com/vb/general/simple-floating-reamer-holder-306442/) and decided to give it a go as the build looked easy. I had a spare chuck and thought I could put it to some use.

The design is easy to understand and build. It is essentially a sort of universal joint with the joints being able to slip radially.

Unfortunately it failed consistently. Holes of various diameters were drilled and bored, then reamed using this holder. Holes resulted oversize by more than .03mm and halfway down the bore opened by .09mm and then returned to .03mm.

Tests were repeated with reamer held in regular chuck. Results were consistently satisfactory.

I was wondering if somebody had ever tried to build this type of holder, maybe I did something wrong.


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## woodchucker (Apr 20, 2022)

Seems like you may have to much play allowing it to wander from parallel 

Sent from my SM-G900V using Tapatalk


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## Rob Thule (Apr 20, 2022)

It's meant to have angular and radial play.


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## benmychree (Apr 20, 2022)

I think that, generally, floating holders are not necessary where there is good alignment between the reamer and workpiece, especially if the chuck holding the reamer is a fairly accurate one so far as true running is concerned; the suspect looking one that you are using may be the source of the problem.  Chucks made for portable electric drill may not necessarily be particularly accurate, no chuck that may cause gyrations of the reamer would be suitable for reaming operations and I do not think that a floating holder would compensate for that situation. Floating holders are made to allow for parallel misalignment between a machine spindle and the cutting tool, in this case, a reamer.


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## extropic (Apr 20, 2022)

@Rob Thule 

Thanks for posting your findings. It could prevent others from barking up that wrong tree.

Sometimes you're the windshield. Sometimes you're the bug.


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## Rob Thule (Apr 20, 2022)

extropic said:


> @Rob Thule
> 
> Thanks for posting your findings. It could prevent others from barking up that wrong tree.
> 
> Sometimes you're the windshield. Sometimes you're the bug.


So true


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## Ken226 (Apr 20, 2022)

I can see how it allows for axial float, but I dont see a mechanism for radial.   What am I missing?


The two axles/pins allow tilt but which mechanism allows it to float while the holders axis remains parallel to the lathes Z axis?

Using that U-joint design, I think you'd need an additional joint and set of pins to get full axial/radial freedom of motion. That single set will only allow for decision from coaxial.  Unless there's another part in there that I can't see.



I designed, built and tested one about a year ago, but a totally different design.  Mine is loosely based on the Hemingway kit version. Not so much in it's design,  but in it's mode of operation.  It allows both radial and axial float,  and also has the ability to be locked and used as a rigid tailstock collet chuck.

I've been using it since, and it works great.  I just used it yesterday to make an ogive comparison.  The holes came out perfect.

Here's a thread I started on mine awhile back.








						ER20 Floating Collet Chuck/Reamer holder files.
					

I just spent a couple hours converting my floating ER20 collet chuck / reamer holder models from Inventor,  over to Alibre Design and recreating the dimensioned drawings.   If any of you guys are interested, I uploaded the drawings in PDF,  hopefully you can download them strait from this post...




					www.hobby-machinist.com
				





Edited to add:

Nevermind..I got it now.   I missed the part in your first post that explained the pin/hole slip fit allowing for radial float.


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## Janderso (Apr 21, 2022)

Did you guys see this?
This guy is the real deal. I subscribed to his channel.

I'm sure benmychree is correct. I've had limited success using my chucking reamers in my Rohm keyless chuck in the tail stock. Sometimes I get a perfect fit, other times it's oversized. Might be the Chinese reamers. Purchased individually, as needed from Travers.

Just for fun, I priced out some aluminum bronze and the 4130 he used to fabricate this tool.
A piece of 3" X 12" aluminum bronze was almost $600 delivered.
I couldn't find any 4130 (it's supposed to be easier machining than 4140??)
I don't have any material that large except a piece of 4" dura-bar that went through the fire.

I'll put this project away for when I win the lottery.
The price of material is so high, I am limited on what I choose to do in my shop.


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## Ken226 (Apr 21, 2022)

Janderso said:


> Did you guys see this?
> This guy is the real deal. I subscribed to his channel.
> 
> I'm sure benmychree is correct. I've had limited success using my chucking reamers in my Rohm keyless chuck in the tail stock. Sometimes I get a perfect fit, other times it's oversized. Might be the Chinese reamers. Purchased individually, as needed from Travers.
> ...



Yes, I saw that video back when I designed the one in my link above.  I used several of his ideas in mine.   They work quite well!

Like you, I decided to pass on the aluminum bronze


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## Chewy (Apr 21, 2022)

My question is do you really need it?  I switched to the Jo Pi method last year and it works perfectly.  You drill the hole 2 sizes or so under size.  Use a boring bar on a light cut to correct any irregularities or mis-alignment, then use the reamer.  The reamer follows the existing hole, just enlarging it.  I have made several motor arbor extensions in the last couple of weeks and to the best of my abilities, they all are within a tenth of perfect. That is checking on the lathe and on the motor.  I have not added any run out anywhere. I looked at the floating reamer here on the forum last year and almost made it.  I started checking my work and couldn't see where I would get any improvement. That is just me.
PM1228 lathe, 5/8 PM keyless chuck, PM AXA setup with steel boring bars.


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## Janderso (Apr 21, 2022)

Chewy said:


> My question is do you really need it?  I switched to the Jo Pi method last year and it works perfectly.  You drill the hole 2 sizes or so under size.  Use a boring bar on a light cut to correct any irregularities or mis-alignment, then use the reamer.  The reamer follows the existing hole, just enlarging it.  I have made several motor arbor extensions in the last couple of weeks and to the best of my abilities, they all are within a tenth of perfect. That is checking on the lathe and on the motor.  I have not added any run out anywhere. I looked at the floating reamer here on the forum last year and almost made it.  I started checking my work and couldn't see where I would get any improvement. That is just me.
> PM1228 lathe, 5/8 PM keyless chuck, PM AXA setup with steel boring bars.


I probably don't need one, but I would love to make one just for the learning opportunity.
I need a project right now.


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## Janderso (Apr 21, 2022)

This looks like a great project!!


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## Ken226 (Apr 21, 2022)

Chewy said:


> My question is do you really need it?  I switched to the Jo Pi method last year and it works perfectly.  You drill the hole 2 sizes or so under size.  Use a boring bar on a light cut to correct any irregularities or mis-alignment, then use the reamer.  The reamer follows the existing hole, just enlarging it.  I have made several motor arbor extensions in the last couple of weeks and to the best of my abilities, they all are within a tenth of perfect. That is checking on the lathe and on the motor.  I have not added any run out anywhere. I looked at the floating reamer here on the forum last year and almost made it.  I started checking my work and couldn't see where I would get any improvement. That is just me.
> PM1228 lathe, 5/8 PM keyless chuck, PM AXA setup with steel boring bars.



In a case where I'm creating the hole that I intend to ream, then probably not.

I use it for reaming (form tool) the chamber in rifled barrel blanks.

In the case of a .338 Lapua Magnum, the chamber is about 3" deep and the reamers pilot is following an existing thru hole that was gun drilled the entire length of 30" long 416R or 4150 cylinder.   A small diameter hole drilled so deep usually has a small amount of curve in the hole. 

A floating reamer holder allows the pilot to follow the hole without stresses causing the pilot to mark the lands.  It also helps reduce the risk of reaming an oversized chamber.

Oversized chambers reduce brass life and make customers cry.  The price of Lapua brass is getting absurd.

That's the theory anyway.

In theory, it should even allow me to just chuck up a barrel blank in a 3 jaw chuck a ream the chamber.  But, I havn't been brave enough to test that on a 400$ Kreiger blank yet.


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## xr650rRider (Apr 21, 2022)

Ken226 said:


> In theory, it should even allow me to just chuck up a barrel blank in a 3 jaw chuck a ream the chamber.  But, I havn't been brave enough to test that on a 400$ Kreiger blank yet.



You'd need a very very good 3 jaw and a barrel that had been center indicated, then trued on OD for it to work.  I spend the time to indicate with a Interapid 312B-15 to get the throat area and chamber dialed in to < .0002", then drill, bore and ream.  If your tailstock is dialed in, then just about any reamer holder will work.  I use a Gre-tan floating holder and probably has $15 worth of parts to make one.  The JGS floating reamer holder is a true work of art if you've ever had one disassembled.  Lots of precision ground surfaces.  Couldn't make one without a surface grinder.  The $800 carbon fiber blanks that you only get one shot are the ones that make me sweat.


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## Ken226 (Apr 21, 2022)

xr650rRider said:


> You'd need a very very good 3 jaw and a barrel that had been center indicated, then trued on OD for it to work.  I spend the time to indicate with a Interapid 312B-15 to get the throat area and chamber dialed in to < .0002", then drill, bore and ream.  If your tailstock is dialed in, then just about any reamer holder will work.  I use a Gre-tan floating holder and probably has $15 worth of parts to make one.  The JGS floating reamer holder is a true work of art if you've ever had one disassembled.  Lots of precision ground surfaces.  Couldn't make one without a surface grinder.  The $800 carbon fiber blanks that you only get one shot are the ones that make me sweat.



Your method sounds the same as mine, except that I use a long reach Tesa indicator.  I pretty much always indicate inside the bore, both ends of the blank between these spiders.








About the 3 jaw,  I meant that I'd like to try it with my shop made floating reamer holder, on a cheap barrel blank, letting it runout all it wants,   Just to see what happens.   To see how well my floating reamer holder really works.. 

But, I don't have a spare action laying around to test fire it on and sure dont wanna strip apart my SPR just for a silly experiment.


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## xr650rRider (Apr 21, 2022)

******* removed as it's derailing OP thread and has nothing to do with it *******


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## Rob Thule (Apr 21, 2022)

benmychree said:


> I think that, generally, floating holders are not necessary where there is good alignment between the reamer and workpiece, especially if the chuck holding the reamer is a fairly accurate one so far as true running is concerned; the suspect looking one that you are using may be the source of the problem.  Chucks made for portable electric drill may not necessarily be particularly accurate, no chuck that may cause gyrations of the reamer would be suitable for reaming operations and I do not think that a floating holder would compensate for that situation. Floating holders are made to allow for parallel misalignment between a machine spindle and the cutting tool, in this case, a reamer.





Chewy said:


> My question is do you really need it?  I switched to the Jo Pi method last year and it works perfectly.  You drill the hole 2 sizes or so under size.  Use a boring bar on a light cut to correct any irregularities or mis-alignment, then use the reamer.  The reamer follows the existing hole, just enlarging it.  I have made several motor arbor extensions in the last couple of weeks and to the best of my abilities, they all are within a tenth of perfect. That is checking on the lathe and on the motor.  I have not added any run out anywhere. I looked at the floating reamer here on the forum last year and almost made it.  I started checking my work and couldn't see where I would get any improvement. That is just me.
> PM1228 lathe, 5/8 PM keyless chuck, PM AXA setup with steel boring bars.


I also use the drill, bore and ream method. It works great in my machines as explained in my first post. I read somewhere that machine reamers should flex enough to follow the hole.

This build was just an experiment which did not involve much effort or material, so why not give it a try. 

I now have an interesting looking keychain :-D


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## Chewy (Apr 21, 2022)

I am familiar with using the floating reamer for chambering barrels.  I believe that was something started several years ago to improve the chambers. If you just want to do it, then go for it.  I do lots of things here just for fun.  Some sit on the shelf for a year or two and then get used a bunch.  Couldn't do the job without them. 
If you would like a challenging job, look at the Jo Pi live tail-stock holder. He put two bearings in a tail-stock holder so they now act as a changeable live center.  I am going to go bigger and longer with three bearings.  I will use it for the live center, micro-drill holder and different size die holders tap and die holders.  Forgot pressure turning adapter. 
Have fun!  Chewy


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## Parlo (Apr 26, 2022)

If a standard size reamed hole is required then use the same size spotting drill & go deep enough to leave a 'size' parallel counterbore before drilling undersize. The reamer will follow the counterbore created by the rigid spot drill.


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## LVLAaron (Apr 26, 2022)

Ken226 said:


> In a case where I'm creating the hole that I intend to ream, then probably not.
> 
> I use it for reaming (form tool) the chamber in rifled barrel blanks.
> 
> ...



I have plenty of barrel sections I could test this with. I always dial on the bore and use a JGS floating holder... but I'd be curious what the neck/throat alignment would look like if I just put a segment in the 6 jaw and dove in.


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## LVLAaron (Apr 27, 2022)

LVLAaron said:


> I have plenty of barrel sections I could test this with. I always dial on the bore and use a JGS floating holder... but I'd be curious what the neck/throat alignment would look like if I just put a segment in the 6 jaw and dove in.



I was thinking through this a bit. 

I pre-drill and bore chambers. It's critical that that the section you bore aligns perfectly with the barrel's natural bore. If the barrel was not straight, but then bored a straight body, the reamer would follow the body until it got up to the neck and then possibly give an oversized chamber, kind of like OP described. You'd have this: >< 

But.... if I didn't pre-drill and bore I think the reamer might stay true enough to keep things consistent. I'll pick up a roughing reamer / chamber core drill and see what happens.


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