sharing some amateur customization

[craneman]

Expecting dials to repeat any closer then .001" is wishful thinking even on a new machine.
You spindle runout is pretty bad. Spindle run out should be less then .0001" but what are you measuring? Wear of the collet taper interface surface or actual bearing run out?? Not critizing your measuring just pointing out the spindle might be fine you just might have wear on the taper were the collet seats.

FYI Bridgeport only guaranties the X&Y to be within .003"over 12" IRRC I can pull up the specs. Thats the spec we worked to on all the rebuild I've done we tried to split that down to .0015" TIR over 12" just to be safe.Problem is with the olde dove tail metal on metal ways you can only make the machine so tight of then it will not want to move. We did scrape one machine into jig bore specs. Squareness to .0005 over 12" but you were still limited by the accuracy of the lead screw for actual distance. So a good DRO is required.
What I'm getting at is I don't think your machine is in as bad of condition as you might think. repeateble to .001" off dial is damn good even on a old machine.

Table condition is another story.

You certainly may be right. I did measure the collet interface. Hmmmmm maybe I should mount a gauge pin and check that way. I don't know how good the actual collet is, but I guess I should check that too.

Maybe you are right and it is better than I thought. I have no specs, and I didn't bother looking. It repeated to .001" in a small area away from the center, and that is where I try to use it at. So I was thinking "good enough for what I do".

I wanted to try to stone the high spots down around the damaged areas on the table, but it is pretty flat and I don't want to screw it up

Thanks for the tips.

[kcstott]

You certainly may be right. I did measure the collet interface. Hmmmmm maybe I should mount a gauge pin and check that way. I don't know how good the actual collet is, but I guess I should check that too.

Maybe you are right and it is better than I thought. I have no specs, and I didn't bother looking. It repeated to .001" in a small area away from the center, and that is where I try to use it at. So I was thinking "good enough for what I do".

I wanted to try to stone the high spots down around the damaged areas on the table, but it is pretty flat and I don't want to screw it up

Thanks for the tips.

Collets even the best have a run out of a few tenths... you need a precision ring gauge to measure spindle runout. you are indicating a perfectly round ground surface so any veriation from zero on the indicator is machine and fixture related. In reality unless the quil is getting really warm I wouldn't worry about it.

the collet surface is what matters as that effects your cutter and your surface finish.

The table Just get a large round stone that a medium to a fine grit. stone the high spots down a bit. don't shoot for a super smooth finish and remove all the dips and ding, just knock down the burrs.

Your vise/fixture will ride on a large surface area and the minor dents and dings will not matter as long as you are not clamping over a depression in the table.

that said if the table is that fouled up and you are claming your slide as you did in the pics.
don't be afraid to take a piece of steel bare stock say 1/2" thick Fly cut it on both sides measure for parallelism set your slide on that and clamp.
It'll add support and make the slide more rigid and not sink into a depression on the table.

Now your serations. I'll tell you a trick on that too...

Us a tap. take an old two flute tap with the proper pitch for your serations and grind off one flute removing all the threads and relieve the other sder leaving only a minor amount of the threads. then run it like an endmill.

You touch off dial in and cut the whole thing in three passes working to full depth. and conveniently taps come in various pitches.

[ar15barrels]

Now your serations. I'll tell you a trick on that too...



Us a tap. take an old two flute tap with the proper pitch for your serations and grind off one flute removing all the threads and relieve the other sder leaving only a minor amount of the threads. then run it like an endmill.



You touch off dial in and cut the whole thing in three passes working to full depth. and conveniently taps come in various pitches.

A thread mill would probably work ok too...

[kcstott]

A thread mill would probably work ok too...

Yeah but these guys ain't going to spend $$$ on a holder and an insert.

[craneman]

Yeah but these guys ain't going to spend $$$ on a holder and an insert.

Yep. For what little work I do for myself. I doubt it would pay. that little HSS cutter was $45 at Mcmaster-Carr. If it doesn't do anything else that was cheap serrations for me.

Thanks for the tip with the tap secondary uses.