Size matters: Arbor too short

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seal killer
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Size matters: Arbor too short

Post by seal killer » Sun Jan 16, 2022 3:17 pm

All--

I wanted to do a little face milling on a piece of aluminum for a current insignificant project. I dug through my stuff and found my face mill. When I mounted it I quickly discovered the arbor is too short. My drawbar will only grab about three threads. No good. All of my R8 stuff is 4" long. The face mill arbor is 3.75" long.

I think I have three options . . .

1. Buy a drawbar 1/4" longer.
2. Get an arbor for the face mill 1/4" longer.
3. Buy a new face mill with the correct length arbor.

If I buy a new drawbar, I do not see why this one for a Lagun Variable Speed mill would not work . . . https://www.mcmaster.com/29705a25/?Srch ... ox=drawbar

Or, maybe an adjustable drawbar . . . https://www.mcmaster.com/29705A23/?Srch ... ox=drawbar
I wonder if the adjustments on this 17.25" drawbar make it longer or shorter? (I need 18.25".)

Instead of a drawbar, should I get an arbor that is 4" long? Here are some at MC . . .https://www.mcmaster.com/r8-shank-end-m ... ox=drawbar
The trouble is I cannot determine the arbor length of any of those shown. What am I missing?

In the photo below, the face mill is the top tool.

Please straighten me out on this. As always, thanks!
--Bill
0115221608_HDR.jpg
You are what you write.

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tornitore45
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Re: Size matters: Arbor too short

Post by tornitore45 » Sun Jan 16, 2022 3:53 pm

A piece of all-thread with nut on top can get the project rolling. You can call it adjustable draw bar, sounds more professional.
Mauro Gaetano
in Austin TX

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Bill Shields
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Re: Size matters: Arbor too short

Post by Bill Shields » Sun Jan 16, 2022 4:08 pm

Been there done that with the all thread..

Is there a wear washer at the top of your drawbar?

Years ago when I needed a new draw bar, I made one that was intentionally too long and added a spacer washer at the top so that I could accommodate a couple of odd ball arbors that had caused me problems over the years.
Too many things going on to bother listing them.

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seal killer
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Re: Size matters: Arbor too short

Post by seal killer » Sun Jan 16, 2022 5:59 pm

tornitore45 and Bill--

tornitore45, I could certainly do all-thread and a double nut. Hardware store all-thread?

Bill, I'll look at my drawbar. I can't remember. Thanks for mentioning that.

--Bill
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tornitore45
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Re: Size matters: Arbor too short

Post by tornitore45 » Mon Jan 17, 2022 7:51 am

Hardware store would work in a pinch but tend to be soft and stretch, eventually.
Depending on size and pitch the hardware store may or may not have it.
A better grade like McMaster sells would make an adequate long-term solution.
It is just for use with one harbor, how often do you run that?
I have a washer on top just because I did not like the idea of rubbing the drawbar head on top of the spindle.
Mauro Gaetano
in Austin TX

earlgo
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Re: Size matters: Arbor too short

Post by earlgo » Mon Jan 17, 2022 10:07 am

Bill wrote
Years ago when I needed a new draw bar, I made one that was intentionally too long and added a spacer washer at the top so that I could accommodate a couple of odd ball arbors that had caused me problems over the years.
That is my solution, too. Long drawbar with spacer.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.

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seal killer
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Re: Size matters: Arbor too short

Post by seal killer » Mon Jan 17, 2022 11:09 am

tornitore45--

McMaster Carr is one of my favorite places to shop. I would rather shop there than, say, my wife's favorite shoe store(s).

--Bill
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Bill Shields
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Re: Size matters: Arbor too short

Post by Bill Shields » Mon Jan 17, 2022 12:50 pm

I make my drawbars from 4140 with hex attached to the top end
Too many things going on to bother listing them.

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liveaboard
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Re: Size matters: Arbor too short

Post by liveaboard » Mon Jan 17, 2022 1:23 pm

I made one; I needed a 5/8" thread for a UK arbor. It's just a long bolt.
No 5/8" threaded rod here, I cut the thread on the lathe.
It's more fun anyway.
I didn't even harden it.

The stock 16mm drawbar that came with the mill is slightly too long for some tools I have with adaptor ends, I use a 10mm shim and it fits well.

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Re: Size matters: Arbor too short

Post by pete » Mon Jan 17, 2022 5:59 pm

Your too short arbor is I think the first time I can recall seeing it mentioned Bill. Afaik there's pretty rigid industry standards for any machine tool taper and shank length. You didn't say or maybe you even remember where you bought that short one. If it's off shore then a non standard length might be not that hard to have show up. If that's what it is, then also check just what draw bar thread that short shank has before you start buying or making another draw bar. Depending on where there ordered or came from originally, it could be either our standard 7/16ths X 20 tpi or a M12 thread. Ordering R8 shanks for any reason from the UK or Europe you have to be careful because most or maybe all of them have metric threads. European company's like Narex export over here and then use the same imperial draw bar thread as we do. At least Narex does that for sure, but I don't know about others. All of my R8 shanks are the same length and thread pitch. There are accessory heads that are purposely designed and come with what's known as a stub length R8 arbor. On the one head I have it's about 2" shorter than those standard length shanks. Most of the 90 degree, all angle, and the Volstro accessory heads I know of use those same stub length R8 shanks so a different length draw bar is required with those. If that was done on purpose then that 1/4" shorter seems like it was just factory penny pinching on material for no good reason. It could also be a factory defect that somehow got through there QC.

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tornitore45
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Re: Size matters: Arbor too short

Post by tornitore45 » Mon Jan 17, 2022 6:35 pm

I may be prejudice and biased here but the Chinese commercial/consumer industry does not waste anything. If they had a drop 1/4" shorter so be it bag it and ship it. QC? What QC?
I was repairing a lamp of some sort and found a bastard thread on the 4 studs. It appeared that rather than junking a run of wrong studs they made matching nuts.
Another fixture had a heavy piece in the base. The best analysis I could muster was a material made of concrete loaded with iron filing. Go figure the reason for choosing such "advanced" material.
Mauro Gaetano
in Austin TX

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Bill Shields
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Re: Size matters: Arbor too short

Post by Bill Shields » Mon Jan 17, 2022 7:45 pm

Waste not...want not
Too many things going on to bother listing them.

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