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Spring meet up in Ontario, April 6/2024. NEW LOCATION See Post #31 Discussion AND THE
NEW LOCATION
@Redneck_Sophistication - that is not too difficult a repair - send me dimensions. The gear is 12 tooth - what is its diameter? If I have the cutter it would not take long.
Looks like the gear is mild steel given the deformation. The shaft can be made out of some 4140 if required.
Just as a potential lead in case you didn't see the link in another thread, you might get lucky and find an off the shelf replacement gear in the Boston Gear spur gear catalog. Boston Gear spur gear catalog. Local source: BDI Canada.
@Redneck_Sophistication - that is not too difficult a repair - send me dimensions. The gear is 12 tooth - what is its diameter? If I have the cutter it would not take long.
Looks like the gear is mild steel given the deformation. The shaft can be made out of some 4140 if required.
For best results, the drill, bore & ream should be done on a lathe as it will be hard to hold that long shaft on a vertical mill. One would want the insert to run as true as possible to the rest of the shaft. Using the same size pin as the original one will give the same shear strength to the finished shaft as you had before it broke.
If your pin is not hardened, I’d use it as an insert in this repair; it is already to size and just needs two cross holes for pins.
I’d even try to salvage the gear for the time being. If you can file the damaged teeth there is probably enough left of them for engagement on the rack. Just clock it such that the two damaged areas (the one on the gear and the other on the rack) do not coincide as the carriage is traversing. This is not a high speed set-up and you should get away with quite a bit of tolerance.
For set up this is what I was thinking:
I’d bought a couple of lathe chucks on the cheap on kijiji (he put “rust coating on them” yeah that’s tremclad primer lol
Clamp that to the table and shim if needed to make sure it’s true to the head and vice versa.
I was thinking some heat, and more the tooth back into place on the spur gear clean up with a file, if it breaks replace the steel with bronze tig. @RobinHood fantastic idea to time the gear tooth away from the rack tooth.
I cleaned up the gear and noticed a name an (part?) Number.
Does this reference anything? Maybe this could be ordered.
@Redneck_Sophistication - that is not too difficult a repair - send me dimensions. The gear is 12 tooth - what is its diameter? If I have the cutter it would not take long.
Looks like the gear is mild steel given the deformation. The shaft can be made out of some 4140 if required.
Brent! I didn’t see this on the third page. Thank you for the offer! That’ll definitely call for a bore gauge if you still need one! Lol
The major diameter of the gear is 1.150,
I thought I could try and fix the shaft and gear to a passable condition and then make a new one to have in reserve if it doesn’t last. But I’m sure you could do a far better job then I. I would definitely compensate you for it, I’ll get better dimensions on it.
@Tecnico thank you for the resource I’ll check that out tonight. Maybe I can find a new gear, now that I have a number on it, maybe it’ll narrow it down.
@David_R8 i couldn’t agree more! You guys are all my brain trust!
@PeterT any components On the lathe are imperial, strange to me if it was a German made lathe :/
Gears are a whole other study. You need to figure out the DP (diametric pitch) and PA (pressure angle) in order to specify the gear properly. Best to let @Brent H take a look at it. He'll have the gages to measure it up (maybe?).
I'm looking for a 28 tooth mate for this 14 tooth gear..... The DP appears to be 16. The only gears that match the required diameters on the McMaster-Car website are 16 DP 14.5 PA gears. So is going with 16 DP 14.5 PA a safe bet?
Using the chuck for work holding is a good idea. You can carefully center it under the mill spindle and do the subsequent operations based on that set-up. I am sure it will work out for you.
As far as dissimilar hardness of metals: since there is no relative motion between the components on the assembled shaft, it does not matter if one part is harder than the other.
Check out the table on the page for all the spec data: 14.5 PA, 12 diametral pitch, 12 teeth, .5" bore. Sounds like we have a winner! Gotta love a manufacturer that puts identifying data on their product.
Nah, this place is filled with people that have collectively been there and done that and are more than happy to pass it on. Great bunch, I've learned my share here and I'm keeping my eyes open because there's so much to soak up.
I have no idea where that saying comes from but it's just plain wrong. A blind squirrel would have zero problems finding nuts. They can smell a nut 4 inches under ground and under a foot of snow. Might be better to describe jumping successfully to the next tree.....
Tomorrow you try single point threading eh! I love cutting threads on a lathe. I'll try to be available as much as possible if you need help.
I have no idea where that saying comes from but it's just plain wrong. A blind squirrel would have zero problems finding nuts. They can smell a nut 4 inches under ground and under a foot of snow. Might be better to describe jumping successfully to the next tree.....
Tomorrow you try single point threading eh! I love cutting threads on a lathe. I'll try to be available as much as possible if you need help.
I've done external threading including some non-book sizes but not internal and tomorrow I'm starting on a test piece before I ruin an expensive hunk of steel. The compound is set, the HSS tool is ground, and it will run in on a boring bar which isn't ideal but it's what I have at the moment. I could spend a large fortune on tooling if I bought everything I wanted!
I have no idea where that saying comes from but it's just plain wrong. A blind squirrel would have zero problems finding nuts. They can smell a nut 4 inches under ground and under a foot of snow.
We will return you to your regular discussion after a pages-long digression into small mammals, vision problems, volatile organics as related to various species of nuts, and the perceptiveness of the olfactory sense in sub-optimal conditions.
Ok well I don’t know much but that looks like something to me.
Was my first time reaming something for real. Also realizing how quick you run out of room on a bridge port even. Need to find a riser ring.
The shaft wasn’t overly hard. File would dig in pretty good. Slightly harder then a piece of mild steel.
I indicated the shaft to the quill with a little .0005 indicator and had it reading perfect just the slight variance in the shaft service.
Ended up with a few thou of run out though. Maybe the drill wondered. Drilled at 31/64 maybe should have gone smaller, let the reamer do more?
Going to go into town this morning and grabs some roll pins. Hopefully get this working.
Current plan is to bribe Brent to make me a shaft as I’m sure he will do a better job then I can. And hopefully find a new gear and then replace this.
The longer stuff is disassembled in my shop the lower it’s life expectancy!
I found the function of all the leavers and was able to label. Half nut is working good, it was the other feed leaver needing to be in neutral having a lock out on the leaver.
I think I might have turned the lathe on with the feed engaged?? Maybe that shock loaded it.
Now that won’t happen (hopefully) that I understand the leavers. Stoked to have my feeds! And cross feed
Check out the table on the page for all the spec data: 14.5 PA, 12 diametral pitch, 12 teeth, .5" bore. Sounds like we have a winner! Gotta love a manufacturer that puts identifying data on their product.
Nah, this place is filled with people that have collectively been there and done that and are more than happy to pass it on. Great bunch, I've learned my share here and I'm keeping my eyes open because there's so much to soak up.
There usually is some backlash between the gear and the rack, so it should still work.
Drill probably did deflect a bit during the process. One can improve the accuracy by boring a “lead-in” the same size as the reamer after you pilot drill the part. This guides the reamer and it does not typically follow the off center pilot. Also, a floating reamer holder helps.
Yes, headroom disappears very quickly when you need to stack things on the table… one way to get around this problem is to “hang parts off the table” and move / swivel the ram around to reach the part.
