Made a gear cutter arbor

Winegrower said:
Yes, that is the single end expanding mandrel I have, let’s say, little confidence in. I have used them for some work successfully. But this type below is far better, since you can use an arbor press to tighten the part on the mandrel.

The set below from eBay is particularly well made, seems to me.

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View attachment 401351
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Since I'm such a beginner, where is the part captured?
 
The two halves of the mandrel pass through the center hole of the part, so it’s like a pig on a spit.
 
Winegrower said:
The two halves of the mandrel pass through the center hole of the part, so it’s like a pig on a spit.
Click to expand...
I gathered that, but where on the mandrel? On the taper? On the slotted part? I'm new at this, so have really no idea, having never used one like this. Not part of my experience base yet.

Edit: Seems to be on the slotted part which is expanded by driving in the taper. How does one unlock them? Tap the slotted piece off? Is the taper hardened?
 
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Winegrower, just curious, why did you have little confidence in this type mandrel?
This one is 1”, they came in blanks, machine to size.
I’m guessing they weren’t accurate enough?
yeah, i couldn’t get them closer than a thou or 2 or so, not good enough for gears, but in the application i was using it for that was plenty good enough.
The parts I was machining for our purpose‘s were 12 or so inches in diameter, and I could hold the part with confidence with this mandrel.
I’ve never seen the type mandrel you show, but I haven’t seen a lot of tools I see on this forum.
One reason I’m here I guess :)
 

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Janderso said:
Stretch yourself. That’s the only way to learn.
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Yes, indeed. Machining for me has been a stretch. Learning how to machine has really exercised my mind in different ways, far more than I had ever anticipated.

Now I look at most things and ask myself, how would I make that? Or, one usually uses tool X to do this, but I don't have that, can I do this using what I have? For me, the latter, is usually the situation. Really fires up your creativity to stretch and apply what you do know to solve problems. Occasionally, one really does need tool X, but more often than not, there are many other ways to accomplish the task. I like that part about hobby machining, at least for me, it makes me think.
 
WobblyHand said:
Yes, indeed. Machining for me has been a stretch. Learning how to machine has really exercised my mind in different ways, far more than I had ever anticipated.

Now I look at most things and ask myself, how would I make that? Or, one usually uses tool X to do this, but I don't have that, can I do this using what I have? For me, the latter, is usually the situation. Really fires up your creativity to stretch and apply what you do know to solve problems. Occasionally, one really does need tool X, but more often than not, there are many other ways to accomplish the task. I like that part about hobby machining, at least for me, it makes me think.
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I am very fortunate to have a wide selection of machine tools and hand tools, machinists tooling etc.
At 65 I can finally spend time in my shop and create, repair, refurbish fabricate whatever comes into my mind.
Unfortunately I don't have a very creative mind.

I appreciate Youtubers who don't assume everyone has their level of tooling.
Tom Lipton is really good about sharing ideas purposely thinking about the hobby guy.

Cheers mate.
 
Manual Mac said:
Winegrower, just curious, why did you have little confidence in this type mandrel?
This one is 1”, they came in blanks, machine to size.
I’m guessing they weren’t accurate enough?
yeah, i couldn’t get them closer than a thou or 2 or so, not good enough for gears, but in the application i was using it for that was plenty good enough.
The parts I was machining for our purpose‘s were 12 or so inches in diameter, and I could hold the part with confidence with this mandrel.
I’ve never seen the type mandrel you show, but I haven’t seen a lot of tools I see on this forum.
One reason I’m here I guess :)
Click to expand...
If I fit the gear blank better it may have held. When I tightened it up I thought it would hold. The design with the tiny allen screws just doesn't seem like you can gronk the pressure needed to hold fast.
I think you may be right. Bad fit could have been my problem.
 
Manual Mac said:
Winegrower, just curious, why did you have little confidence in this type mandrel?
This one is 1”, they came in blanks, machine to size.
I’m guessing they weren’t accurate enough?
Click to expand...

Janderso said:
Bad fit could have been my problem.
Click to expand...
Yes, I think this analysis is correct…
1) starts with poor fit
2) which causes over expansion of mandrel
3) which means contact is a ring rather than a cylinder
4) and requires excessive tightening of a relatively tiny screw thread
5) which makes slippage quite likely, especially for heavy or interrupted cuts.

But the single ended expandable mandrel has worked a few times, and that I’m now aware of these limitations I can use it when it makes sense. But for heavy duty, the double tapered mandrels are the ticket.
 
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