MetalworkingFun Forum

(12-19-2014, 08:23 PM)dallen Wrote: [ -> ][quote pid='39089' dateline='1419038217']
in that case they may get filed down with some tape on the leaf to stop the file from marring the surface. He should know what he's doing he's been building classic guns for a long time and been a machinist for a long time, but then there's always that one time when things got butt up and stuff crashes. just thinking about it, it can't be done on the surface grinder using a Mag Chuck cause of the two bearings sticking out the side that would be on the chuck.

David

Does your friend have a good pair (or large single) magnetic transfer parallel? It could be done that way with the bearing points hanging over the edge, similar to how I did the orginal form grind of the .310 radial feature that is bigger than the .152 (or so) width.

An open, hard grade free-cutting and friable structure wheel of about 46 grit would be the key.

(12-19-2014, 11:52 PM)PixMan Wrote: [ -> ]

(12-19-2014, 08:23 PM)dallen Wrote: [ -> ][quote pid='39089' dateline='1419038217']
in that case they may get filed down with some tape on the leaf to stop the file from marring the surface. He should know what he's doing he's been building classic guns for a long time and been a machinist for a long time, but then there's always that one time when things got butt up and stuff crashes. just thinking about it, it can't be done on the surface grinder using a Mag Chuck cause of the two bearings sticking out the side that would be on the chuck.

David

Does your friend have a good pair (or large single) magnetic transfer parallel? It could be done that way with the bearing points hanging over the edge, similar to how I did the orginal form grind of the .310 radial feature that is bigger than the .152 (or so) width.

An open, hard grade free-cutting and friable structure wheel of about 46 grit would be the key.

[/quote]
Ken
I don't know just what he has to work with, they have a pretty good selection of tools there at the school where he teaches. I'm not going to get in a hurry with a file, one thing I made myself promise me was that I would not get in a hurry with this and screw it up. So far I've helt to that promise except for one little mix up on the stock where we cutout a butt stock that wouldn't work because it was too short and too narrow to fit the butt plate.
So the little pins that are sticking up will get trimmed, just not sure when. Probably one day when I wake up and say todays the day the pins get trimmed and the shop monsters not raising cain, and the tickers not bothering me.
What I'll probably do is put it in a vise with the leaf set just low enough that the file won't touch it. and file them down, take all of ten minutes.
DA  

Do be careful squeezing that part in a vise. Even if you have a vise that can grip the full length, try to get it gripping only on the ends where it doesn't have the slot extending and is solid across.

The reason I didn't hold it in my grinding vise is that I didn't want to collapse that slot in the middle at all. It's not going to take much pressure to distort something that thin.

Was tied up with a few Christmas things (humbug) but stole some time today to grind a cutter and this evening cut the acme thread. Even at 100 rpm that carriage is hard to stop at 5 tpi.
Wish I knew what this steel was, machines to a respectable finish and seams quite hard.





Need to cut a 1 mm pitch thread on the other end to lock the thrust bearings, and a small keyway.
Soon have the old girl back in good health.

It looks darned good to me Greg

Nice work Greg! So it is an Acme thread after all then, eh? I thought you had said it was a square looking thread.

The 1mm thread should be easy as long as you don't have to go through the steps I do to change the gears. On my lathe I have to remove the collet closer's notched wheel to be able to open the end cover of the machine and get to the gears.

5tpi - pure luxury that is. Try threading with a 2tpi leadscrew and no brake!

Top job on that screw Greg.

Greg

nice looking parts

DA

As mentionned on the "other" forum, where did you find that clean horizontal surface. LOL

Thanks guys.
My bad Ken, when I first looked at it I thought it looked square, at least not acme, turns out it was metric, 30 deg but for some reason they also cut the thread way to deep, as in the tip of the cutter was too narrow. I ground mine to match the tread, then checked it with my 29 deg acme thread fish, the tip was about two sizes too narrow so I ground it off to match the 5 tpi gauge slot. Seams to clear. When I have it apart to install the new screw I'll measure the minor dia on the old one. The pitch dia is right using the three wire measure.
The metric thread is a flip of the lever on this lathe, but not the Hardinge.
This lathe has a 2 tpi leadscew as well Mayhem and only an internal wet brake. Stops pretty good but I did manage one slight crash into the shoulder. The half nuts on this lathe are way to stiff and the leaver too low to use for threading so I just leave them locked and go back and forth with the clutch. It will cut down to 1/4 tpi, I could probably enter the carriage in drag races on that setting.
Steve, if I was sensitive at all I'd take offence to your brutal attack on my shop hygiene. Actually brought it into the kitchen to admire it at the table, which by the way hadn't got wiped after dinner, Charlie had done the dishes for me while I was playing in the shop.