# Horizontal Milling Arbor



## francist (Jun 12, 2019)

I decided I needed to cut some gears, it seems to be a popular thing these days. The key word here is "decided", not "discovered", making this purely an adventure of desire rather than actual necessity. But it's a hobby, right? It's supposed to be fun.

Anyway, to cut said gears I would need gear cutters of which I had none. And the gear cutters I could find for the pitch I wanted (24 DP) all came with a 1" arbor hole. I have two arbors, both 7/8" diameter, of course. Hmmm....

I started with a piece of 1-1/4" 1018. I would have preferred 12L14 but my regular source is no longer stocking a lot of it anymore so 1018 was pretty much my only local option. 

The spindle this has to fit has a #2 Morse taper and 3/8"-16 drawbar threads, so I needed to get those into the end of my 11" long bar somehow and without a steady rest. I opted to just mark out for centres by hand and then drill them using the drill press. In the same setup, I drilled and tapped the one end for the threads. Then I put a short hex bolt into the lathe collet, drilled a centre in the head, and then threaded that into the newly threaded drawbar end to reclaim the centre for turning the shaft.

And after all that talking, here it is on the lathe. I wasn't sure if I would get movement in the bar going from 1-1/4" down to 1", so I roughed all the dimensions first to about 50-thousandths oversize. It's been a while since I've turned between centres but I find I quite like it. At first I was getting quite a lot of chatter, so I changed from my ball bearing centre to a solid one and it quickly disappeared.




This was my first time cutting a Morse taper, and also the first time using the offset tailstock method. It works great! I would have liked just a hair better fit though, but I ran out of diameter before I could make that happen. It locks in ok and I think it will work, just didn't get quite as nice a bluing as I was hoping for. Next time.




I did get the main 1" diameter on the money though, as well as the threads for the arbor nut. Did I mention this is for a horizontal machine? Well it is. 







There also needs to be a collar just ahead of the Morse taper that can engage the drive dogs. Rather than having to use a bigger, bigger bar and turn the collar integral to the arbor, I decided to thread one on separately. And in order for that not to undo itself under load, it would have to be left hand threads. First time for those too.







Cutting the keyseat for the full length of the shaft was less than elegant but it got done, and when the dust had settled all the pieces fit together. I still need a few more gear cutters to make up a set, but I've got two or three to play around with in the interim. 




Thanks for looking!




-frank


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## markba633csi (Jun 12, 2019)

Nice job Frank- I like your little 3-sided tool post also, it's cute as a bug
Mark


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## francist (Jun 13, 2019)

Thanks Mark. My objective was to try to get maximum tool footprint but still maintain full rotation without hitting the little hump on the compound. I don't know that it accomplishes that any better than others, but it was an interesting exercise. And it's still my go-to post.

-frank


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## Martin W (Jun 13, 2019)

Great work Frank. Very professional looking. 
Cheers
Martin


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## f350ca (Jun 13, 2019)

Very nicely done Frank! Interesting that the solid center helped with the chatter, will try that.

Greg


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## buffdan (Jun 13, 2019)

very nice, inspiring.. Thanks for sharing


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## brino (Jun 13, 2019)

Hi Frank,

Lots of "firsts" for you on this project.
It appears they all turned out very well.

It is inspiring, thanks for sharing!

-brino


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## francist (Jun 13, 2019)

Thanks Brino, and yeah you're right -- quite a few firsts on this project.

I actually thought a little about that when I'd finished. These operations aren't complex by any stretch, but if you haven't done them before you are hesitant because you're not sure how to go about them. It made me wonder at what stage in our process we become comfortable with trying something, where we derive the confidence from. 

I've often felt that as we get older and try new (for us) things, we sometimes expect that we should know how to do them right away. After all, we've spent our whole working lives knowing what we do. We forget that we still have to learn, regardless of how old we are. You can't just think "I'm good, no need to learn the basics here, already spent 50 years doing that...". Fortunately I've always liked learning from the ground up, the down side is that there will likely not be enough time to learn all the basics for all the things I want to learn to do!

-frank


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## brino (Jun 13, 2019)

Frank,

My problem is that I only get into my shop for a few hours a week.
Maybe I've done an operation before, but it was so long ago I forget much of what I knew when I last did it.



francist said:


> Fortunately I've always liked learning from the ground up, the down side is that there will likely not be enough time to learn all the basics for all the things I want to learn to do!



Good thing I like learning too, because I get to re-learn some things every year or two. 

-brino


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## Bi11Hudson (Jun 13, 2019)

Like you, I was cutting gears on the Atlas horizontal, an MF-B. In my case, the mandrel was one inch. I considered trying to make a 7/8" for the gear cutters. But much of what I do is in metric. And the (cheap) metric gear cutters have metric centers. In several sizes... I would end up with half a dozen chunks of steel to care for, et al. 

What I ended up doing was acquiring a number of MT-2 single ended mandrels. They had spacers and lock nuts and worked well enough. Some had 3/8-16 hold downs, some metric at M10X1.5 which is so close to 3/8-16 that if you sneeze you'll miss the difference.

The caveat, of course there's one, is that most of my work is fairly small, under 1-1/2 inch. The single ended mandrels would fit, but brought the work close to the column. The indexer had to be set over near the inside edge of the table. Doable, but things were very close. The indexer won't fit past the column, that sort of close.

On the other hand, I have a cheap (HF) Chinese vertical milling machine I usually use for a small drill press. By getting an adapter from R-8 to MT-2,  the vertical machine will work (I think) to hold the cutters. I haven't tried it yet, but it looks like it will work. I don't know how far it can open up, a 16 DP. 127 tooth gear is a handfull. But I want to at least *try *to make one, one day.

Which brings up a* theory*. There are milling cutter holders that are MT-2 to whatever. I use 1/2 inch adapters. The sort that uses 3/8-16 hold downs... A mandrel of some specific size cut down to 1/2 inch on one end and the over arm bearing on the other. And the appropriate flat on the 1/2" end plugged into the milling adapter. On the MF-B, the overarm can be run in or out as needed. So the mandrels needn't be full length. Only 8" would be long enough. The biggest issue would be collars, keyways, lock nuts, that sort of thing. 

Why oh why didn't I think of that *before* I spent all that money on the short mandrels. Ces't la vie... Not enough coffee, perhaps. Of course, such a mandrel probably wouldn't stand up to working hard metal, but brass or aluminium with a slow feed should work OK.  What think you?

The metric gear cutters came from China, Russia, all sorts of Far East countries. They may or may not be _that _accurate, but my builds work well enough. The biggest issue is that they were cheap, under $100 *per set* of 8. The only hold back is bore size, they're all over the map.

It works for me, I don't know about you. But worth looking into.

Bill Hudson​


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## francist (Jun 13, 2019)

Bi11Hudson said:


> It works for me, I don't know about you. But worth looking into.




Hmmm, interesting. I did think of using a milling cutter holder (aka end mill holder) as a source of the MT2 end and turning off the "holder" portion. The arbor part could then be attached to that.

In part I steered clear of turning down a perfectly good end mill holder and also in part because I could not verify the construction method of this holder. It looked (at least as far as I could see down the dark interstices) was that the taper and the holder were a marriage and not turned from one solid lump of metal. This brought to mind a previous fellow who had tried something similar only to discover that under significant load (he was using a 4" diameter horizontal milling cutter) the married parts became un-married. Great excitement happened!

My logic, flawed as it may be, was that my circular cutter at 2-plus inches in wheel diameter would likely load the holder more than a, say, half-inch shank end mill and if the holder was indeed two pieces press-fit together I didn't want to find that out under power. I doubt a gear cutter would do that, but I figured if I had the arbor I would soon enough end up with a larger milling cutter of similar bore and be inclined to use it. There were also thoughts about the sleeves and if tightening the arbor nut would want to draw the stub arbor out of the holder (I guess a stop collar could prevent that) and also the end mill holder typically does not have provision for the drive dogs. At least the ones I have don't, so spinning in the taper became a concern. Again, not necessarily with a gear cutter or a half-inch end mill, but with a larger wheel cutter.

I think in the end I had so many unknowns about repurposing the holder that they outweighed the unknowns about making one from scratch! So I went from scratch. I did make it shorter than the regular arbors though, by about two inches, as most gears should end up being cut centred on the table anyway.

I like your suggestions though, and I expect they would work well for what you do. Thanks for bringing them up!

-frank


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## francist (Jun 24, 2019)

Well, aside from the usual goat rodeo that happens when I do something new for the first time, it appears to work. Overshot the bore for the tapered mandrel and had to Loctite the blank on, undersized the wheel diameter by nearly 10 thousandths, but still managed to pull off 44 teeth 24 DP in aluminum. Lots of fun! 

Thanks for looking.

-frank


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## T Bredehoft (Jun 24, 2019)

Frank, you gotta be proud of that, I surely would be.


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## francist (Jun 25, 2019)

Thanks Tom, I appreciate you saying that. 

-frank


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## FOMOGO (Jun 25, 2019)

That came out great Frank. Nice when a plan comes together on the first attempt. I too am familiar with the old goat rodeo. Cheers, Mike


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## brino (Jun 26, 2019)

Frank, it looks perfect from here!
-brino


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## francist (Jun 26, 2019)

Thanks Brino!


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## stioc (Jun 26, 2019)

francist said:


> View attachment 297196



Wow, that came out really nice. Did you chamfer the edge of the teeth on the lathe?


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## francist (Jun 26, 2019)

Thanks, and yes I did.

 I turned the blank slightly oversize, drilled and reamed (in retrospect I could have bored and got a better fit to the mandrel), mounted blank to mandrel, turned to final OD and chamfered the two edges, then took the whole affair to the indexing centres to cut the gear. So really, cutting the teeth was my last operation.

-frank


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