My band saw broke!!

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shootnride
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Re: My band saw broke!!

Post by shootnride »

GlennW wrote: Wed Nov 10, 2021 7:21 am Grooved with this.
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Kennametal Multidirectional Tool. It will turn, face, groove, and part. It is quite stout as I have turned with it to full depth.
Glenn,
Any chance you could provide some specifics (part numbers, etc.) for this tool. I got on the Kennametal website and found what I believe is that tool, but the smallest shank size they seem to offer is .750 which is a bit large for my 14" lathe. Just wondering if that's what you're using. That tool appears to be exactly what I've needed on numerous occasions.
Thank you
Ted
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GlennW
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Re: My band saw broke!!

Post by GlennW »

It's been in the tool holder for years, so apparently I forgot what it actually was. Probably out of production now, as I quit using Valenite because they changed things regularly and constantly discontinued them.
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Here's a link to a catalog I just found online. No telling if it is current or 15 years old.
https://cnctar.hobbycnc.hu/VarsanyiPete ... arting.pdf

Page 190 lists it as a Turning, Grooving, Profiling tool.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
pete
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Re: My band saw broke!!

Post by pete »

As usual really well done and great surface finish Glenn.

Those necked down axle shafts might be for a safety or just a parts saving reason BadDog. One where if the part fails it's designed to do so at that point first. A great design engineer would of course catch something like this automatically. I wonder if today with the really high end design and failure analysis computer programs that there capable of catching what the design engineers sometimes might miss. I've seen more than a few times where a fairly cheap part failure on mining equipment took out some very expensive additional components that would have been fine had the part failed farther away from hoses, pumps etc. One in fact where a small air compressor worth maybe a couple of grand had it's connecting rod fail and punch through the casting on me and then took out a $35k engine in a grader. A simple $20 sensor down on the machines belly pan would have enough to get a warning in the cab. I think I'd agree with Bill about this band saw part, it was just overlooked as a designed in weak spot and likely modified later with I bet a different part number once someone noticed that it could be a possible built in failure point. A good object lesson about leaving those sharp inside corners, except at Glenn's expense. Pretty amazing how a few small radii can make all the difference.
Last edited by pete on Wed Nov 10, 2021 8:13 pm, edited 1 time in total.
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BadDog
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Re: My band saw broke!!

Post by BadDog »

You comment regarding "parts saving reason" is exactly what I was originally thinking. By creating a "fuse" it's limiting the max torque that can be forced through the system breaking more expensive, harder to replace, or dangerous parts.

As far as modern computer software detecting it, I think it's quite common now to run a FEA (Finite Element Analysis) on CAD drawings during design. I've seen the heat maps showing huge warning indicators where too small (or no) fillet is specified. In that case, I think (no experience) it would be pretty clear exactly how much torque it would take before failing. Then again, how old is the plan for that drive being used, and how recent were manufacturing details changed to increase productivity without an engineering review? Like parts coming from China where they meet spec long enough to lull customers into complacency, then start cutting corners anywhere that helps their margins. From that point on it's a tug of war between the two competing interests to get suitable parts to ship product.
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TimTheGrim
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Re: My band saw broke!!

Post by TimTheGrim »

BadDog wrote: Tue Nov 09, 2021 3:39 pm I may be misinformed, but axle shafts sometimes feature a necked down portion that I've been lead to believe is specifically for that purpose. Particularly in front shafts. Maybe a myth, but I've heard that argument put forward for other things as well. However, these instances are "neck down" areas without sharp corners, so maybe that's the key difference.
The “Series” Land Rovers had rear axles that were tempered back at a specific spot so that they would break there instead of overtaxing a less replaceable upstream drive line component. Once the axle broke at that spot, it was a relatively quick and easy repair in the field. I and my fellow L-R buddies ALL carried a spare set of axles when we we out clowning around in the rough.

The front axles were bullet proof.

My ‘71 Series IIA was particularly susceptible to axle breaks. One month after I bought it on a “Mechanics Lean” with a freshly rebuilt transmission, the motor sucked in the timing chain and self destructed. A quick 10.5 months later it had a factory fresh low compression Ford 289 short block with 302 heads, a Holley 650 Spreadbore, a GM alternator, fresh hand done wiring, gauges and a set of Thrush side pipes. It was fun but the trans was not full synchro so then I upgraded to a 4 speed top loader from a 351 Torino with a Dana transfer case and a Warn Overdrive. 16 forward and 4 reverse speeds. It beat ‘70s smog Corvettes up to 80 mph before the steering got scary and I had to back off. I could break a rear axle at will but only did that once.

Very nice job and info on your repair. Thanks for posting .📐⚙️
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'96 Birmingham mill, Enco 13x40 GH and Craftsman 6x18 lathes, Reid 2C surface grinder. Duro Bandsaw and lots of tooling from 30+ years in the machining trades and 15+ years in refinery units. Now retired
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GlennW
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Re: My band saw broke!!

Post by GlennW »

Got the grinder set up and ground the three bearing journals. Out of time for more...
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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
shootnride
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Re: My band saw broke!!

Post by shootnride »

GlennW wrote: Wed Nov 10, 2021 1:03 pm It's been in the tool holder for years, so apparently I forgot what it actually was. Probably out of production now, as I quit using Valenite because they changed things regularly and constantly discontinued them.
DSC03756.JPG

Here's a link to a catalog I just found online. No telling if it is current or 15 years old.
https://cnctar.hobbycnc.hu/VarsanyiPete ... arting.pdf

Page 190 lists it as a Turning, Grooving, Profiling tool.
Thanks Glenn. I will do more research. It does appear that Kennametal makes a comparable tool, but I would have to reduce the tool shank to fit my tool holders. I've done that on a couple of tools, but it's always nicer if the correct size is available.
Ted
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Bill Shields
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Re: My band saw broke!!

Post by Bill Shields »

You can find similar if you look for Swiss type machine tooling.

They tend to have smaller shanks.

What you are looking at is a very common tool.
Too many things going on to bother listing them.
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GlennW
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Re: My band saw broke!!

Post by GlennW »

Everything ground but the threads. Just need a couple of keyways cut now.
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The worm wheel just slides on but will sty in place. Gotta love grinding!
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Glenn

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Harold_V
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Re: My band saw broke!!

Post by Harold_V »

Hmmm. I'm wondering why you didn't cut the keyways before grinding. They're known to release internal stress, causing the shaft to distort.
Have you found any evidence of movement?

Beautiful outcome, Glenn.

H
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GlennW
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Re: My band saw broke!!

Post by GlennW »

Harold_V wrote: Sat Nov 13, 2021 2:42 amHmmm. I'm wondering why you didn't cut the keyways before grinding. They're known to release internal stress, causing the shaft to distort.
Actually, I never gave it a thought until now! :oops:

I'll watch it and see how it reacts.

Thanks!!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
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GlennW
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Re: My band saw broke!!

Post by GlennW »

First keyway cut for a 5/16" square key. The TIR was 0.0000" before the cut at the center of the shaft between centers, and 0.0000" after the cut using a B&S .0001" DTI. (I grind with the drive end center "dead", not rotating)
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The other keyway is a woodruff key at the opposite end, so I expect no change after that one as well.

Better lucky that good!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
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