Compound Slide Repair Question

Compound Slide Repair Question

Stumpy
Stumpy

March 6th, 2012, 6:01 pm #1

Got a question about the compound slide on my Harbor Freight 9x19 Mini Lathe.

In removing the tool post for disassembly and cleaning I came across two screws with stripped out heads. I drilled the heads off just fine but when attempting to drill out the shank the bit wandered without my noticing and now I've got an oblong hole.

http://www.grizzly.com/products/G4000/parts/13

The screws are part #14 and they thread into the bottom of part #2 which is the base of the compound slide. The screw holes are set 120° apart and there is a pin which helps locate part #5 (the angle indicator). Neither Harbor Freight nor Grizzly can get the part for 2 months and I ofcourse have a project that needs a part made before it can go any further.

Drilling out the oblong while remaining centered would be tricky and I can't really go up a thread size anyway because the screw heads must fit inside a .450X.180 counterbore in part #5. I could retap the holes 60° out from the current ones but part #5 is the angle dial and that would throw the dial way off. I could drill it out and make a threaded plug but I can't do that without a lathe. I'm fairly certain welding would warp it to the point of requiring a rescraping (besides it's probably cast iron) but would it be possible to braze the hole in and then retap without distorting the base? Is there a better option I don't see?

I can wait two months if I absolutely have to but that'll really annoy me.

Thanks in advance,

Matt
Quote
Share

Maker of Toys
Maker of Toys

March 6th, 2012, 8:24 pm #2

nutated threads.
Quote
Share

Russ Kepler
Russ Kepler

March 7th, 2012, 3:46 pm #3

Got a question about the compound slide on my Harbor Freight 9x19 Mini Lathe.

In removing the tool post for disassembly and cleaning I came across two screws with stripped out heads. I drilled the heads off just fine but when attempting to drill out the shank the bit wandered without my noticing and now I've got an oblong hole.

http://www.grizzly.com/products/G4000/parts/13

The screws are part #14 and they thread into the bottom of part #2 which is the base of the compound slide. The screw holes are set 120° apart and there is a pin which helps locate part #5 (the angle indicator). Neither Harbor Freight nor Grizzly can get the part for 2 months and I ofcourse have a project that needs a part made before it can go any further.

Drilling out the oblong while remaining centered would be tricky and I can't really go up a thread size anyway because the screw heads must fit inside a .450X.180 counterbore in part #5. I could retap the holes 60° out from the current ones but part #5 is the angle dial and that would throw the dial way off. I could drill it out and make a threaded plug but I can't do that without a lathe. I'm fairly certain welding would warp it to the point of requiring a rescraping (besides it's probably cast iron) but would it be possible to braze the hole in and then retap without distorting the base? Is there a better option I don't see?

I can wait two months if I absolutely have to but that'll really annoy me.

Thanks in advance,

Matt
If you can't helicoil it drill waay up on the old hole, thread something handy and use red or green loctite to secure a plug. Face off the plug, drill & tap for the original thread.
Quote
Share

Chipmaker
Chipmaker

March 7th, 2012, 5:40 pm #4

Got a question about the compound slide on my Harbor Freight 9x19 Mini Lathe.

In removing the tool post for disassembly and cleaning I came across two screws with stripped out heads. I drilled the heads off just fine but when attempting to drill out the shank the bit wandered without my noticing and now I've got an oblong hole.

http://www.grizzly.com/products/G4000/parts/13

The screws are part #14 and they thread into the bottom of part #2 which is the base of the compound slide. The screw holes are set 120° apart and there is a pin which helps locate part #5 (the angle indicator). Neither Harbor Freight nor Grizzly can get the part for 2 months and I ofcourse have a project that needs a part made before it can go any further.

Drilling out the oblong while remaining centered would be tricky and I can't really go up a thread size anyway because the screw heads must fit inside a .450X.180 counterbore in part #5. I could retap the holes 60° out from the current ones but part #5 is the angle dial and that would throw the dial way off. I could drill it out and make a threaded plug but I can't do that without a lathe. I'm fairly certain welding would warp it to the point of requiring a rescraping (besides it's probably cast iron) but would it be possible to braze the hole in and then retap without distorting the base? Is there a better option I don't see?

I can wait two months if I absolutely have to but that'll really annoy me.

Thanks in advance,

Matt
Is there any reason you can't modify part 5 as well?
What else do you have available? Drill press, mill, ect.

My first inclination would be to open up the existing M6 threaded holes to .25 with an endmill fed painfully slowly to try to minimize deflections from the oblong stock. Then chase with an "F" drill- or say screw it, haha- and thread it 5/16-18UNC. Than modify part 5 to accommodate, or modify the screw heads by grinding, cutting, polishing, whatever.

Filthy dirty option 2, I would reassemble part 2 to part 5 with the locator pin and remaining useful screw. Then I'd drill through part 5 into part 2 using whatever tap drill size you like. Disassemble, open up holes in part 5 to clear the threads, tap part 2, and provide screw head relief. The beautiful part here is that with patience, you could probably pull this one off with a hand drill. Might have to counter sink and use a flat head screw, but it'll get you making chips.

There are many, many better, cleaner options, but sometimes, cheap, quick, and accessible supersede the need for perfectioin. I've been there.

-Chad
Quote
Share

Stumpy
Stumpy

March 8th, 2012, 1:36 am #5

I thought you had it for a bit, I hadn't considered increasing the size of the counterbores. However the counterbores are already an 1/8th away from the center hole. I tried to upload some pictures but neither of my picture hosting sites are cooperating tonight.

I've got a decent size Jet-16 mill drill but I don't trust that the table is flat, my old man once tried to surface the table on the machine. I've tried squaring several parts on it before and they've come up crooked. I have a bandsaw and a drill press and that's about it.

I measured the oblong and it's out far enough to remove it while remaining on the original center I'd need to go up to 3/8 or bigger. I got careless and now I'm paying the price.

Your filthy option (good name for it!) I'll save as a last resort as that'll destroy another not so cheap part but it's another option I hadn't considered, thank you!

Can anyone offer some advise about warping at brazing temperatures?
Quote
Share

Stumpy
Stumpy

March 8th, 2012, 7:24 pm #6

Got a question about the compound slide on my Harbor Freight 9x19 Mini Lathe.

In removing the tool post for disassembly and cleaning I came across two screws with stripped out heads. I drilled the heads off just fine but when attempting to drill out the shank the bit wandered without my noticing and now I've got an oblong hole.

http://www.grizzly.com/products/G4000/parts/13

The screws are part #14 and they thread into the bottom of part #2 which is the base of the compound slide. The screw holes are set 120° apart and there is a pin which helps locate part #5 (the angle indicator). Neither Harbor Freight nor Grizzly can get the part for 2 months and I ofcourse have a project that needs a part made before it can go any further.

Drilling out the oblong while remaining centered would be tricky and I can't really go up a thread size anyway because the screw heads must fit inside a .450X.180 counterbore in part #5. I could retap the holes 60° out from the current ones but part #5 is the angle dial and that would throw the dial way off. I could drill it out and make a threaded plug but I can't do that without a lathe. I'm fairly certain welding would warp it to the point of requiring a rescraping (besides it's probably cast iron) but would it be possible to braze the hole in and then retap without distorting the base? Is there a better option I don't see?

I can wait two months if I absolutely have to but that'll really annoy me.

Thanks in advance,

Matt
Figured it out. A guy on another forum pointed out all those screws do is hold the dial to the compound base. They don't contribute to tool post rigidity or accuracy. I can bolt it back together sans screw and run it normally. A fine example of slow down and think it through. I'll run as such til I'm done with my current project and then do a plug repair later this summer. Thanks for your help guys, especially you Chad.

Matt
Quote
Share

Chipmaker
Chipmaker

March 8th, 2012, 9:53 pm #7

Maybe, hopefully, I'm missing something. I don't have hands on experience with your model lathe, but the parts diagram makes it look loosening the nuts (17) is what allows the compound to rotate and be set at different angles. Is that right? And said bolts exert force on the clamping ring (4) which in turn applies pressure to the graduated dial (5). If that's the case those screws 100% account for the strength and rigidity of the compound. Just not seeing any other mechanical link between the carriage and the compound, and I don't want to see anyone hurt or sustain other damages.

-Chad
Quote
Share