# Made a gear cutter arbor



## Janderso (Mar 18, 2022)

I recently picked up a set of the 8 gear cutters for the 14.5 degree pitch.
I did not have an arbor for the mill to hold them.
A quick project.
I may need a longer tool. We will cross that bridge when we get there.
I have the NT30 spindle. No R8. You can buy R8 gear cutter arbors all day long.


----------



## Brento (Mar 18, 2022)

Nice. How much did that set cost you?


----------



## MtnBiker (Mar 18, 2022)

That R8 thing. Simultaneously great for plentiful options and ultimately not that great of a design. I wish Bridgeport had gone with a more robust attachment all those years ago.


----------



## Winegrower (Mar 19, 2022)

I’ve been happy with how easy it is to make arbors for saws and various cutters.   And by turning everything in one setup, the runout is almost zero.

I bought a set of modulus 1.5 for around $80.  It’s very straightforward to cut modulus gears, but one generally needs a dividing head.


----------



## cathead (Mar 19, 2022)

What are you planning to make with the 20DP cutters?  Also curious if you are going to use
the Gorton RT to make the gears.  I have made a lot of gears using my RT and it works great.


----------



## Janderso (Mar 19, 2022)

Brento said:


> Nice. How much did that set cost you?


Hmm, I think it was about $80
This is the 20 DP
Small little guys. 7/8” ID


----------



## Brento (Mar 19, 2022)

I am always looking for gear cutters bc i just love the idea of cutting gears.


----------



## WobblyHand (Mar 21, 2022)

Janderso said:


> I recently picked up a set of the 8 gear cutters for the 14.5 degree pitch.
> I did not have an arbor for the mill to hold them.
> A quick project.
> I may need a longer tool. We will cross that bridge when we get there.
> I have the NT30 spindle. No R8. You can buy R8 gear cutter arbors all day long.


Nice work Jeff.  

Interesting that individuals have some things that are easy for them and just do them, but others would hesitate.  For me, having flubbed up an arbor, I'd hesitate making this.  Guess we all come from different backgrounds.  I'm just barely developing machining talents, whereas it seems you can just do things like this as a quick project.  

Keep at it, you are an inspiration.


----------



## Janderso (Mar 21, 2022)

My first gear.
I learned a bunch!
I need a more substantial holding fixture for the gear.
It moved about hakf way through.
Also, i second guessed myself. Diameter over pitch is my depth. I looked at the wrong figure in my notes and cut too deep.
Next time it will be perfect.


----------



## Just for fun (Mar 21, 2022)

That looks really good Jeff.  Does the gear go to anything?


----------



## DavidR8 (Mar 21, 2022)

I'd be right proud if I made that!
Well done Jeff.


----------



## Janderso (Mar 21, 2022)

Just for fun said:


> That looks really good Jeff.  Does the gear go to anything?


It sits in my reject pile


----------



## brino (Mar 21, 2022)

Janderso said:


> It sits in my reject pile



For me it would be on a trophy shelf!
Even if not perfect over 99% of people would not be able to tell.
Just say it was not up to "your personal standards".

What moved?
Were you locking the RT between passes?
Would a tailstock have helped?

Thanks,
Brian


----------



## ErichKeane (Mar 21, 2022)

Nice!  I've cut gears on a few occasions and have a few learnings:

1- The rotary table needs to be locked, otherwise the gear can take up the backlash and screw you over.
2- The only 'good' arbor I've ever had for those is a home-made mandrel that uses whatever interior fixture on your gear holds it (like a set screw, key/etc), PLUS a bolt off the end compressing it.
3- Because of #2, grab a 4 jaw and indicate in the mandrel!
4- Cut as close as you can to the chuck, but no closer( or your chuck gets gear teeth ).

I've NEVER had the tailstock help at all FWIW.  I'd rather use a center bolt to help hold on the mandrel. The side load on the gear blank is pretty minimal anyway, most of the force is rotational or towards the chuck.


----------



## Janderso (Mar 21, 2022)

WobblyHand said:


> Nice work Jeff.
> 
> Interesting that individuals have some things that are easy for them and just do them, but others would hesitate.  For me, having flubbed up an arbor, I'd hesitate making this.  Guess we all come from different backgrounds.  I'm just barely developing machining talents, whereas it seems you can just do things like this as a quick project.
> 
> Keep at it, you are an inspiration.


Those are very kind words. I appreciate it very much.
When you are just having fun and you don’t have a boss or schedule to satisfy, it’s just quality time in the shop.
Stretch yourself. That’s the only way to learn.


----------



## Janderso (Mar 21, 2022)

brino said:


> For me it would be on a trophy shelf!
> Even if not perfect over 99% of people would not be able to tell.
> Just say it was not up to "your personal standards".
> 
> ...


The gear slipped in the mandrel. I trued to keep the forces light by being patient.
Maybe a tapered mandrel and a tailstock.
I watched a video where they put a 1.5 degree taper in the mandrel. That’s easy enough.
I won’t use an expanding arbor next time I can assure you. I haven’t been too impressed with these cheapos.


----------



## Winegrower (Mar 22, 2022)

I had good luck with the type of expanding mandrel that is two tapered wedges pressed together so they expand evenly and without a taper.   The kind that expand with a screw in the end, I have little confidence in.


----------



## Janderso (Mar 22, 2022)

Winegrower said:


> I had good luck with the type of expanding mandrel that is two tapered wedges pressed together so they expand evenly and without a taper.   The kind that expand with a screw in the end, I have little confidence in.


I have a couple of those. Haven’t used them yet. Good to hear they worked for you.


----------



## WobblyHand (Mar 22, 2022)

Winegrower said:


> I had good luck with the type of expanding mandrel that is two tapered wedges pressed together so they expand evenly and without a taper.   The kind that expand with a screw in the end, I have little confidence in.


Is this the style you have no confidence in?


Used it to turn the outer edge of an 8" aluminum disc.  30mm OD.  Uses a tapered 5/16-18 SHCS.  1045 steel, shop made.  Guessing I was lucky that day.


Can you show a picture of the dual wedge type mandrel?  I'd like to try making gears sometime, so having a good mandrel seems like a good idea.


----------



## Winegrower (Mar 22, 2022)

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.


----------



## WobblyHand (Mar 22, 2022)

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.
> 
> ...


Since I'm such a beginner, where is the part captured?


----------



## Winegrower (Mar 22, 2022)

The two halves of the mandrel pass through the center hole of the part, so it’s like a pig on a spit.


----------



## WobblyHand (Mar 22, 2022)

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.


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?


----------



## Manual Mac (Mar 22, 2022)

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


----------



## WobblyHand (Mar 22, 2022)

Janderso said:


> Stretch yourself. That’s the only way to learn.


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.


----------



## Janderso (Mar 22, 2022)

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.


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.


----------



## Janderso (Mar 22, 2022)

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.
> ...


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.


----------



## Janderso (Mar 22, 2022)

Manual Mac said:


> I’ve never seen the type mandrel you show


It's the same type you have in your comment.


----------



## extropic (Mar 22, 2022)

Janderso said:


> snip>
> *I have the NT30 spindle.*  snip>



Good Arbor.

What brand/model mill do you have (with NT30)?


----------



## Winegrower (Mar 22, 2022)

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?





Janderso said:


> Bad fit could have been my problem.


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.


----------



## Janderso (Mar 22, 2022)

extropic said:


> Good Arbor.
> 
> What brand/model mill do you have (with NT30)?


Sharp TMV. It came with an R8 or a 30 taper.


----------

