- Joined
- Apr 29, 2019
- Messages
- 2,060
A clearance hole for a #8 screw can be easily closed with the mig and no backing needed. I have filled much bigger holes with the mig. Either way you will have to machine and/or grind both sides.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
HSS Lathe Tools chipping, what might cause this?
- Thread starter WobblyHand
- Start date
- Joined
- Jan 2, 2014
- Messages
- 8,852
I would MIG, but only because I'm still terrible at TIG.
Yes, just a copper sheet underneath will peel right off. You may have to flip it and fill a small divot that was originally against the copper.
Once both sides are machine/ground it's like the mistake didn't happen.
-brino
Yes, just a copper sheet underneath will peel right off. You may have to flip it and fill a small divot that was originally against the copper.
Once both sides are machine/ground it's like the mistake didn't happen.
-brino
- Joined
- Dec 18, 2019
- Messages
- 6,447
Unlike my plasma cutter, my MIG welder did work! (Hobart 187, C25 gas, 0.023 wire) Didn't quite fill the holes perfectly, but good enough! I actually practiced it ahead of time, by making some similar holes 1/8" through and 5/16" counterbore in some scrap. Welded it directly to my table. Just gave each weld a tap and it broke of the tiny piece that was stuck to the table. Gee, this is almost like an eraser! 
Interesting HAZ zone, just a circular zone about 1/2 in diameter. Just machined off the big lumps on the weld side. Next is to flip it over and get the little bumps off.
Interesting HAZ zone, just a circular zone about 1/2 in diameter. Just machined off the big lumps on the weld side. Next is to flip it over and get the little bumps off.
- Joined
- Dec 18, 2019
- Messages
- 6,447
Since honing was so onerous, I found some honing plates on e B a y. They are 75x170x1mm. I made a flat plate from some 3/8 aluminum to put the plate on. Much better surface to use rather than my old swaybacked desktop.
Finished the table and mounted it on the belt grinder. Ground two edges of a new 3/8 blank on it. The long first cut is no good. I'm rocking the tool on the grinder. The hone is flat, the tool isn't.
I notice a couple of things are wrong. 1) There's too much gap between the table and the platen. That's fixable. 2) The belt seems to have stretched. Hope there is enough adjustment range in the belt adjuster. 3) With a 120 ceramic grit belt, the tool gets kind of hot. Hot enough that it's hard to hold down flat to the table. I tried 120 rather than the 40 grit, reasoning that it might be easier to hold flat. Of course it takes longer to grind, but the gouges are finer, so the honing might not take as long.
So, I'm making a holder for the lathe tool bit. (A fixture.) This helps in two ways. The first is it's 1" wide rather than 3/8". This should make it easier to keep flat. Also it's longer than a lathe tool bit, so it's easier to hold. 2) The increased mass of the holder will allow a little more grinding before having to cool down. The holder is modeled after a QCTP bit holder. Milled out a slot in a piece of 5/8 x 1" stock. Will add in some 6mm set screws to lock the tool bit in place. Still figuring out how I'm going to hold the piece so I can cut a slot in the corner so the lathe tool bit will go flush to the corner. Will use a slitting saw to make the cut. This is what I have so far.
Cut needs to go in the corner like the figure below.
Finished the table and mounted it on the belt grinder. Ground two edges of a new 3/8 blank on it. The long first cut is no good. I'm rocking the tool on the grinder. The hone is flat, the tool isn't.
I notice a couple of things are wrong. 1) There's too much gap between the table and the platen. That's fixable. 2) The belt seems to have stretched. Hope there is enough adjustment range in the belt adjuster. 3) With a 120 ceramic grit belt, the tool gets kind of hot. Hot enough that it's hard to hold down flat to the table. I tried 120 rather than the 40 grit, reasoning that it might be easier to hold flat. Of course it takes longer to grind, but the gouges are finer, so the honing might not take as long.
So, I'm making a holder for the lathe tool bit. (A fixture.) This helps in two ways. The first is it's 1" wide rather than 3/8". This should make it easier to keep flat. Also it's longer than a lathe tool bit, so it's easier to hold. 2) The increased mass of the holder will allow a little more grinding before having to cool down. The holder is modeled after a QCTP bit holder. Milled out a slot in a piece of 5/8 x 1" stock. Will add in some 6mm set screws to lock the tool bit in place. Still figuring out how I'm going to hold the piece so I can cut a slot in the corner so the lathe tool bit will go flush to the corner. Will use a slitting saw to make the cut. This is what I have so far.
Cut needs to go in the corner like the figure below.
- Joined
- Aug 12, 2014
- Messages
- 269
Had some lathe tool holders with internal corners rounded. Hit them with a Dremel with an abrasive blade hand held at about 45 degrees.worked well.
John.
My diamond hones are considerably larger. Makes it easier for me to maintain a uniform stroke. I made a simple holder for the hones that attaches to a counter. I have a tube that drips water on the hone. Once I have got the surface to be honed positioned flat on the hone I lock both elbows against my body and only move my entire body in an effort to not change the angle of the tool. I'm not a fan of belt grinders for sharpening. I've got an 8" bench grinder with two of the relatively soft white wheels. I use a star type dresser to keep the faces sharp & flat. I try to use two hands and not rest the tool on the machine, only my hands touch the tool rest. The resulting grind is concave making it very quick to get the cutting edge honed. I think it also reduces the likelihood of doing a rounded edge.
I've never had HSS chip. I get a better finish with HSS than with carbide inserts. I gave up on the import inserts after I finally bit the bullet and paid a kings ransom for a box of name brand ones. I buy the ones with a larger nose radius. I keep one inserted tool that I use re-ground inserts in. Fairly esy to do the regrind on a diamond wheel. They get used on rusty, scaly steel. Crappy finish but saves the good tools for the finishing pass.
I've never had HSS chip. I get a better finish with HSS than with carbide inserts. I gave up on the import inserts after I finally bit the bullet and paid a kings ransom for a box of name brand ones. I buy the ones with a larger nose radius. I keep one inserted tool that I use re-ground inserts in. Fairly esy to do the regrind on a diamond wheel. They get used on rusty, scaly steel. Crappy finish but saves the good tools for the finishing pass.
- Joined
- Dec 18, 2019
- Messages
- 6,447
So finished mounting the "scrap" table to the grinder. You can see the HAZ affected area from my welding. Adjusted the table closer to the belt. Not quite sure how to increase the tension on the belt, save for inserting a shim under the spring. Have to think about that.
Finished the machining of the tool holder. First use of my slitting saw! Boy that was a big scary setting up for the first time. Got things lined up, was ready to go and heard this strange thumping. What's that? Oh! It's the saw spindle nut whacking the vise. Some quick thinking, and figured out a solution. Kind of weird doing this, but this angle vise isn't that great anyways... Machined off 0.125" off the back of the angle vise, using a roughing mill. Gave the clearance needed without compromising the vise much. Why is such a huge long nut on the saw arbor necessary? The thing feels like it is half a mile long.
Finally was able to make the cut with the saw. Apparently I was too lazy to flick off that little chip before taking the picture. Whoops!
Fits much better now. Holes are drilled and tapped for 6mm. Still need to cut down the set screws. Have 16mm long set screws, but 10mm long would allow the set screws to just be flush with the surface.
Finished the machining of the tool holder. First use of my slitting saw! Boy that was a big scary setting up for the first time. Got things lined up, was ready to go and heard this strange thumping. What's that? Oh! It's the saw spindle nut whacking the vise. Some quick thinking, and figured out a solution. Kind of weird doing this, but this angle vise isn't that great anyways... Machined off 0.125" off the back of the angle vise, using a roughing mill. Gave the clearance needed without compromising the vise much. Why is such a huge long nut on the saw arbor necessary? The thing feels like it is half a mile long.
Finally was able to make the cut with the saw. Apparently I was too lazy to flick off that little chip before taking the picture. Whoops!
Fits much better now. Holes are drilled and tapped for 6mm. Still need to cut down the set screws. Have 16mm long set screws, but 10mm long would allow the set screws to just be flush with the surface.
- Joined
- Dec 18, 2019
- Messages
- 6,447
Larger than 3" x 6.625"? Where did you get them? Gee, thought these were huge!
- Joined
- Dec 18, 2019
- Messages
- 6,447
An update. Even using the fixture rested against a clamped guide on the table resulted in a grind that was not good. I removed the belt and ran a straight edge against the platen. The steel platen is worn out. So I am going to have to try to inset a glass platen into the cast steel platen. In the past, (Before Mill) it wasn't conceivable to do this mod myself. Now that I do have a mill, I have been pondering how I would do it. I just received a 2"x8" piece of pyroceram. Guess I have to take the belt grinder apart and have at it.
The L shaped platen is an odd shape, it's about 18" long, 3" wide (give or take, depending where you measure from), and about 7 inches deep. Item #28 in the figure below. Since I'd be milling out a pocket, (on the top face) I'd like to support it pretty well. I was thinking of using 246 and 123 blocks to hold the platen on the mill table. I don't have any 246 blocks at the moment, but that's fixable.
The L shaped platen is an odd shape, it's about 18" long, 3" wide (give or take, depending where you measure from), and about 7 inches deep. Item #28 in the figure below. Since I'd be milling out a pocket, (on the top face) I'd like to support it pretty well. I was thinking of using 246 and 123 blocks to hold the platen on the mill table. I don't have any 246 blocks at the moment, but that's fixable.
It looks like the platen location in relation to the belt is adjustable. I would just glue the glass to the steel and move the platen back a little to compensate for the thickness. I used JB Weld to glue mine on, and it isn't going anywhere.