the old grind
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Repairing sheared impeller shaft - JD 47 snowblower attachment
- Thread starter DanMc77
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The decision was made to leave the tap and let it serve as one of the "pins" in the interface. A syringe was filled with slow curing JB Weld and the gap in the flutes was used to inject epoxy down in around the tap to secure it in place. The pneumatic glue dispenser, normally used for solder paste, was very handy. Also, the tapped holes were filled to about 25% full. Each M6-1.0 bolt was given a small slot for epoxy to vent from as the bolt was screwed into place. Bolts were trimmed off and cleaned up on the lathe.
The first bearing was heated up for a few minutes on the wood stove, and it slipped right on with no resistance. It almost immediately locked up and before I could check anything. I noticed that it didn't completely bottom out on the back side. A feeler gauge tells me that there's a .010" gap back there. Not good. I used a punch to tap on the bearing inner race, hoping to get it to seat the rest of the way. It's not moving. It's possible that my radius on the shaft is a bit too much and it's bottoming out there. An order was just placed for a set of radius gauges, so I don't repeat this mistake.
Thankfully there's enough of the back of the bearing to grab onto, so the bearing was able to be removed with a bearing puller. Dodged a bullet on that one!!!
I'll retry this once the radius gauges arrive, and I can figure out why it didn't fully seat.
The first bearing was heated up for a few minutes on the wood stove, and it slipped right on with no resistance. It almost immediately locked up and before I could check anything. I noticed that it didn't completely bottom out on the back side. A feeler gauge tells me that there's a .010" gap back there. Not good. I used a punch to tap on the bearing inner race, hoping to get it to seat the rest of the way. It's not moving. It's possible that my radius on the shaft is a bit too much and it's bottoming out there. An order was just placed for a set of radius gauges, so I don't repeat this mistake.
Thankfully there's enough of the back of the bearing to grab onto, so the bearing was able to be removed with a bearing puller. Dodged a bullet on that one!!!
I'll retry this once the radius gauges arrive, and I can figure out why it didn't fully seat.
pmsmechanic
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Do you still have the old bearing? You could saw a piece out of the inner race with a chop saw, lay it against the shaft, and use that to check for radius fitment.
This is one of the old bearings. I bored the shaft out from underneath it. It dropped off before the cutter reached the bearing itself.
It would be a more positive check to use the bearing race itself, but now that I know that I can pull the bearing off fairly easily, I can tweak the fillet and give it another try. The radius gauges should arrive on Sat and I won't have any time to work on this again 'till next week since I'm sneaking off to spend the weekend in New Hampshire, back in the woods. Nice reprieve from the recent madness in our country.
It would be a more positive check to use the bearing race itself, but now that I know that I can pull the bearing off fairly easily, I can tweak the fillet and give it another try. The radius gauges should arrive on Sat and I won't have any time to work on this again 'till next week since I'm sneaking off to spend the weekend in New Hampshire, back in the woods. Nice reprieve from the recent madness in our country.
jthibodeau89
Gold Member
Is the fillet made by the cutter's corner radius or did you blend manually?
That's where I went wrong. I didn't make a cutter that defined the radius. Now that I'll have radius gauges, I'll be able to grind an HSS cutter with a proper radius. The bearing is a common trailer wheel bearing, so it's easy to find a spec with the radius they use.
jthibodeau89
Gold Member
Ahhh, HSS cutter. I haven't used one of those in 15 or 20 years. First was brazed carbide, now I use indexible carbide inserts. Working in an automotive OEM engine plant spoiled me; 500,000sq ft with 300+cnc centers and a $1.5MM tooling inventory was nice. We machined forged steel cranks, and aluminum heads and blocks at the equivalent of a motor every 20 seconds or so.
ruffdog
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The OP's lathe may not spin fast enough to achieve surface speed for carbide.
Yeah, and the OP is working in the basement on a limited budget. This project did force me to spend some time learning about carbide inserts. Most of my machining instruction is from high school machine shop close to 40 years ago!
The HSS cutters are easy to customize and dirt cheap.
the old grind
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Arthur R Warner Co also makes HSS inserts that use same tool-holders as carbide. I know one guy who uses them.
Carbide inserts costs less but are scrapped when all working corners are chipped, prefer higher SFM and tool pressure because they tear vs cut. Warner's HSS inserts come slightly o/size and can be honed to keep sharp.
Larger diameter workpiece gets SFM up there but toolpost rigidity can make or break ya. That's why Dave likes the Warner HSS for gun work with his Grizzly G0709. Of all those offered I like the 55* & 60 deg threading-grooving inserts on a 3/8" IC, despite 3x cost of same in carbide. Grizzly lathes are far from tops for threading steel.
*Mauser TNMC 32 NV 55 Degree
I also like HSS for undercutting a shoulder when a radius isn't called out, eg to seat a bearing.
Carbide inserts costs less but are scrapped when all working corners are chipped, prefer higher SFM and tool pressure because they tear vs cut. Warner's HSS inserts come slightly o/size and can be honed to keep sharp.
Larger diameter workpiece gets SFM up there but toolpost rigidity can make or break ya. That's why Dave likes the Warner HSS for gun work with his Grizzly G0709. Of all those offered I like the 55* & 60 deg threading-grooving inserts on a 3/8" IC, despite 3x cost of same in carbide. Grizzly lathes are far from tops for threading steel.
*Mauser TNMC 32 NV 55 Degree
I also like HSS for undercutting a shoulder when a radius isn't called out, eg to seat a bearing.