update: rigid reamer holder

[xr650rRider]

 

[SKWERLZ]

It's only "dialed" in to that machine at that specific location on the bed. If your bed is perfect and has no wear, then the dialed in aspect may be true from chuck to tail stock, but many are using older lathes with some wear and the bed height is different depending on location along the bed.

That what I worry about.

 

[Bronsin]

A 7/16 pin does NOT fit into a 7/16" hole. They are the SAME..NO clearance. Either the pin is small or the hole is big. No ifs ands or buts. Same means just that...SAME. Which means there is no clearance.

Would you please inform the engineers I work for about this? They are under the impression that the lines on the drawing somehow represent clearance.

IMHO, there is just nothing wrong with using a floating holder as long as a reamer will follow the hole that it's put into.

The reamer has no choice to do anything other than follow the hole. The cutting pressure equalizes on the flutes and forces it to center itself no matter what is holding it. Even if it's crooked. That's why I always bore a hole before finish reaming it. A bored hole is as centered as you can get.

 

[LVLAaron]

I finally found a couple MT3 "stubs" or adapters that would be suitable. Like anything, "You go to shcool on your first one"


I'm boring with a polished insert (meant for aluminum) to get a cleaner cut with less cutting pressure. Wheeler said somewhere, the reason these maybe work is because there's some play in the tailstock. I found the play.

There's half a thou there on the dial.

I kept going past my dimensional target to see if I could get a light enough cut to make it work. I found if I run the tool to the bottom of my hole. Move the cutting tool 2 thou "bigger", and back the tailstock out slowly, I get virtually no movement and a very nice finish.

Will take another stab at it tomorrow.

 

[TaperPin]

I finally found a couple MT3 "stubs" or adapters that would be suitable. Like anything, "You go to shcool on your first one"


I'm boring with a polished insert (meant for aluminum) to get a cleaner cut with less cutting pressure. Wheeler said somewhere, the reason these maybe work is because there's some play in the tailstock. I found the play.

There's half a thou there on the dial.

I kept going past my dimensional target to see if I could get a light enough cut to make it work. I found if I run the tool to the bottom of my hole. Move the cutting tool 2 thou "bigger", and back the tailstock out slowly, I get virtually no movement and a very nice finish.

Will take another stab at it tomorrow.

Very cool project. It’s funny how watching a short lathe video instantly puts the mind in overdrive as it tries to make sense out of it and prioritize where to focus, while at the same time in the background making a bulleted list of things to watch out for. Lol

Will you ream, or use a blind barrel lap to fine tune the final size?

I‘m excited to see how it works.

 

[LVLAaron]

Very cool project. It’s funny how watching a short lathe video instantly puts the mind in overdrive as it tries to make sense out of it and prioritize where to focus, while at the same time in the background making a bulleted list of things to watch out for. Lol

Will you ream, or use a blind barrel lap to fine tune the final size?

I‘m excited to see how it works.

Haven't made up my mind on the final fit. I want to try and lap it.

 

[TaperPin]

Haven't made up my mind on the final fit. I want to try and lap it.

I’m always impressed with how a lap can take off small amounts so accurately.

 

[LVLAaron]

Progress.

MOST of that wobble/runout in my short video was the body of the tool rubbing... so I turned down the body of the tool to fit and provide some clearance.

I took probably 30 slow passes to keep tool pressure down. (It really is amazing how little you can take off with G type inserts.

Right now, I can fit a .437- pin in there but not the reamer, which is 2 tenths larger than the pin. A little polish and a warm fart should cut enough off there for the right fit.

 

[LVLAaron]

BTW: Using the indicator in lieu of a torque-able tailstock. I'm tightening it down half a thou on the indicator

 

[xr650rRider]

BTW: Using the indicator in lieu of a torque-able tailstock. I'm tightening it down half a thou on the indicator

I annealed and cut off the drive end of a cheap harbor freight impact socket that matched the diameter of the lock down lever shaft and welded it on. Easy to use a torque wrench to be consistent locking down the tailstock.

 

[LVLAaron]

Ran it on a stub of an old 6 groove 6mm barrel.

It's definitely a different/improved experience. You can feel the lands being cut. You can hear metal cutting.

I put a tenths indicator on the finished chamber... Nothing. With the floater It's not uncommon to read a tenth or two out of round on the body.

I'm sold on rigid. Maybe not this exact setup... but I'm really happy with this....

Except it interferes with my flush tray (bread pan) because the tailstock is 3 inches closer to the headstock.

 

[xr650rRider]

Say it isn't so!! Remember to match mark holder so you can insert in tailstock exactly the same next time.
Also handy to put 2 set screws for the reamer shank.

 

[LVLAaron]

Say it isn't so!! Remember to match mark holder so you can insert in tailstock exactly the same next time.
Also handy to put 2 set screws for the reamer shank.

Screw goes on top. Easy to remember. And yes, it needs a second screw.

 

[FireMedic]

Ran it on a stub of an old 6 groove 6mm barrel.

It's definitely a different/improved experience. You can feel the lands being cut. You can hear metal cutting.

I put a tenths indicator on the finished chamber... Nothing. With the floater It's not uncommon to read a tenth or two out of round on the body.

I'm sold on rigid. Maybe not this exact setup... but I'm really happy with this....

Except it interferes with my flush tray (bread pan) because the tailstock is 3 inches closer to the headstock.



View attachment 1498012

This seems to be working for some folks, but I just can’t convince myself that an oversize chamber isn’t imminent with a setup like that.
Something moves .0005 and your chamber is now .001 oversize

I believe a rigid reamer fixed in a block mounted to the carriage would be a better setup than the tailstock setup.

 

[LVLAaron]

This seems to be working for some folks, but I just can’t convince myself that an oversize chamber isn’t imminent with a setup like that.
Something moves .0005 and your chamber is now .001 oversize

I believe a rigid reamer fixed in a block mounted to the carriage would be a better setup than the tailstock setup.

No disagreement from me. I just wanted to experience it, and this was the easiest way to do so.

 

[xr650rRider]

Screw goes on top. Easy to remember.

That's back to being hand grenade close.

 

[xr650rRider]

I believe a rigid reamer fixed in a block mounted to the carriage would be a better setup than the tailstock setup.

If only a normal carriage had that fine z-axis control. If you have a ballscrew/servo, tailstock mounted on a toolholder or plinth, compound set at 0 degrees, then sure.

 

[LVLAaron]

That's back to being hand grenade close.

It's technically, screw on top, then rotate it as until the tang bottoms out, if that makes sense.

 

[LVLAaron]

If only a normal carriage had that fine z-axis control. If you have a ballscrew/servo, tailstock mounted on a toolholder or plinth, compound set at 0 degrees, then sure.

Agree. I can't see using a carriage mounted system on a manual. Unless it's a "carriage mounted tailstock" like Tooley has.

 

[Tucker65]

Progress.

MOST of that wobble/runout in my short video was the body of the tool rubbing... so I turned down the body of the tool to fit and provide some clearance.

I took probably 30 slow passes to keep tool pressure down. (It really is amazing how little you can take off with G type inserts.

Right now, I can fit a .437- pin in there but not the reamer, which is 2 tenths larger than the pin. A little polish and a warm fart should cut enough off there for the right fit.



View attachment 1497905

What's the tolerance of the reamer mfg's shank? I bet you'll find that you'll need multiple rigid holders if you want a fit as good as you made on your initial holder.

If I were to attempt this I'd be looking for a high quality straight shank er collet chuck. Then I'd mount a solid block where my tool post goes and bore that with the boring bar mounted in the lathe chuck. Bore it with about a .001 interference fit and shrink it in.

You'd be relying on the quality of the collet chuck and collets you purchase but the reamer would be held solid and you could feed it in with the compound to have a good feel of how it's cutting.