# 3 size cutter arbor-



## ErichKeane (May 1, 2020)

SO, I have been working on a small hit/miss engine (see my other thread!) and two of the parts it says to buy are brass gears.  However, the place that sells them no longer exists ("Small Parts"?), and googling the model number he gives aren't enough.  Additionally, "Boston" gear doesn't have anything that is of the right dimensions either (it requires a sizable 'hub' section).  SO, I get to make my own!  Travers sent me 2 gear cutters for the 20 and 40 teeth gears, but I don't have an arbor to hold them.

Additionally going through my drawer, I managed to end up with 2 other cutters as time went by (with no way to hold them either!), so I figured I'd try to do all 4 cutters!  The centers are: 1.25 (a 3/32" cutter), 1" (the two gear cutters), and a 7/8" (for a 1/8" thick cutter that I just seem to have).

I started with a hunk of 1 3/8" 1140 that I had leftover from another project:
	

		
			
		

		
	




A quick facing cut, then I went to cut down the part that gets held in the collet.  I'm aiming for 7/8" for 2 reasons: 1- I'm lazy and it is the largest collet I have in both R8 and 5C, and 2- I rationalized that the bigger this is, the better.
	

		
			
		

		
	




Checking that the collet fits!  I then cleaned up this side a bit with some scotch brite and a file.




I flipped it around and put it in the collet chuck.  however, before that, I used the bandsaw to take ~1" off of it, which i figure will be useful for the cap. Started with a facing cut:



Then I started to cut the spot for the cutters!



And here is the small 1.25" center hole cutter, and it fits!  I used a very rounded over cutter for roughing/smooth cutting, then a pointy one to get into the back so that the cutter lays flat.




Here is my gear cutter on its spot on the arbor!



I missed the 7/8" slot, but you get the idea!   I then center drilled and tapped for 1/4-28.  Why 1/4-28?  Because I meant to do 1/4-20, and grabbed the wrong tap.  Such is life:





And this part is done!  I had some leftover "presto blue" from the last time I used 1140.  However, I gave up on that one for 2 reasons: 1- I spilled most of it, and 2- It didn't react immediately like I see with youtubers.  This time I dunked it and gave it some time so it turned black, and I'm glad I did! it looks much cooler!




Tomorrow I'll try to make a clamping cap (or 2 or 3?, maybe one for each size?) to hold my cutter in place. I've seen a coupler of people do these without cutting the keyway, and since my first project is in brass I might skip that part as well.  I'll have to see how effective/necessary it is.  Though, its easy enough to cut a key (or make drilled/tapped hole for a set screw to act as key).


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## Canus (May 2, 2020)

I'd go with something larger than 1/4-28 to handle the torque you are going to need to apply to secure your cutters.


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## ErichKeane (May 2, 2020)

Canus said:


> I'd go with something larger than 1/4-28 to handle the torque you are going to need to apply to secure your cutters.


Hmm... you might be right.  I looked around on a few home-made ones just now and the biggest I saw is about 3/16" threads?  That said, I'm pretty limited by what taps/drills I have on hand, I'm not sure I have anything bigger  

That said, maybe I SHOULD cut the keyway...


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## ErichKeane (May 2, 2020)

Alright, I finished this up today!  I didn't get a chance to use it as I still don't have my chuck for my rotary table, but I was able to make blanks today.  However, this arbor needed to be done anyway.

First, @Canus suggested making the clamping hole bigger, and I think he's right, so I found a pair of 3/8-16 taps (which uses a 5/16 bit  ), chucked up the arbor, and drilled/tapped it.  Hopefully this will hold it better.  I also have a 1/2-13 tap, but this will hopefully be enough. 




I took the cutoff scrap of 1140 and put it in the chuck.  I drilled through 3/8 clearance for the bolt, then used a HSS boring tool to cut these two cutouts.  First, this will only work for the middle section cutter (maybe the smaller one?  Though not auto-centering).  Anyway, thats all I need for now.

Parting off was an adventure, the collet chuck started slipping, so I cut it off with the bandsaw, flattened it with the mill, then hit it with the sander. 



I also used the leftover cold blue to darken it, but it turned out bad.  I didn't intentionally degrease (besides by wiping  it down), so that is probably why.  Here it is with a cutter attached!




Anyway, thats all there is for this project!


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## brino (May 2, 2020)

Erich,
Nice work on the arbour!

okay, I am picking nits here, but the cutter is on backwards......at least for normal vertical mill or lathe use.
I know you probably just stuck it on for a test and the photos, and here I am being "that guy".....

However, I once was just about to cut with a slitting saw, had it centred and ready....and only at the last second realized that I had the slitting saw on the arbour backwards....that would have wiped the teeth off real quick.
So now I try to picture the intended rotation every time I install one.

-brino


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## ErichKeane (May 2, 2020)

brino said:


> Erich,
> Nice work on the arbour!
> 
> okay, I am picking nits here, but the cutter is on backwards......at least for normal vertical mill or lathe use.
> ...


heh, good note!  That was definitely just test-fit/photo op, but I'll definitely make sure to take a 2nd look when I install it to run for real! In this picture, I was making sure the clamping action would work right.


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## Tozguy (May 3, 2020)

Good work on the arbour.
I made some arbours for slitting saws not too long ago. A pin was added in the arbour to fit the notch in the saw. 
For milling cutters like you have even with the larger bolt I would not trust the hold. Since the cutters come with a key notch  it would be easy to add a pin in the arbor to fit in the key notch of the cutter.


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