Floating reamer experiment

[Janderso]

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.

 

[Janderso]

This looks like a great project!!

 

[Ken226]

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.

 

[xr650rRider]

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.

 

[Ken226]

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.

 

[xr650rRider]

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

 

[Rob Thule]

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.

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

 

[Chewy]

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

 

[Parlo]

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.

 

[LVLAaron]

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.

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.