Another order of operations question... re: saw arbor

WobblyHand

WobblyHand

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Since I'm a proud owner of a Niagara slitting saw, thought I'd make an arbor for it. Found a nice plan for a saw arbor @ saw arbor plan There are two pieces, the body itself and a close fitting cap.

How do I ensure the two pieces are concentric with each other? If machined them together, should one hold the cap end and put the shank end into a live center? Thought I'd machine it together as one piece and part the piece between the body and the cap. Both the body length and the cap length are not critical. Then put the body in a 4J chuck to bore out the 1.000" hole. At that point there will be an already turned cap to use to ensure a tight bore fit. Does this make sense?

As a beginner, it takes me a long time to think these kinds of things through. Appreciate any pointers to avoid lovely paper weights!
 
Why not make the shank/body have the post profile and the cap slip over that? That's how I made mine. Then you can make the post portion a perfect tight fit for the saw blade center hole, and if the cap is a tiny bit loose it's not a biggie. My blade was 1/2" hole so I used a 1/2" reamer on the cap and it fits the body very well. I can post a picture if you want
-Mark
I believe I turned the shank (1/2" also) first in the 3-jaw, then flipped it around and held it in a 1/2" collet for the remaining operations, then made the cap
 
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I did one a while back, here is the order of operation that I used.

First I turned the shank and left a bit for the radius to be turned with a 1/4 inch router bit
1596817385031.png

Then flipped it around and did the work on the nose
1596817463791.png

Showing the fit of the saw with the protruding nose, in this case I was using a 4'' carbide saw blade.
1596817598631.png

I had previously done the work on the cap, don't have any pictures of that. It's just a mirror of the face of the arbor. Final cut on the OD of the assembly was done in this setup.
1596817747281.png

Now I need to countersink the screw hole for a flat head screw. I could have done this in a separate operation, but it was just sitting there in place so.....
1596817900895.png


and
1596817998667.png

and the final assembly
1596818079687.png

and cutting the slot that the arbor was made for.
1596818163270.png
 
markba633csi said:
Why not make the shank/body have the post profile and the cap slip over that? That's how I made mine. Then you can make the post portion a perfect tight fit for the saw blade center hole, and if the cap is a tiny bit loose it's not a biggie. My blade was 1/2" hole so I used a 1/2" reamer on the cap and it fits the body very well. I can post a picture if you want
-Mark
I believe I turned the shank (1/2" also) first in the 3-jaw, then flipped it around and held it in a 1/2" collet for the remaining operations, then made the cap
Click to expand...
I agree, the slitting saw arbor in that design is overly complicated and would end up in less accuracy. At BEST, you're going to have a tight fit in the center section, which will give you a 'CLOSE' fit. On the other hand, a version like markba633csi (above) just posted while I was typing this, the nut side doesn't have to be concentric at all!

See this project I did a while back: https://www.hobby-machinist.com/threads/3-size-cutter-arbor.83946
I have 2 nuts for it now so that all 3 of the sizes works, but it is very simpilar to Mark's.
 
I used 1/4-28 also, it's more accurate-ish and less likely to loosen
 
I guess I must be missing something here, the cap fits into the arbor. Make the cap first and size it so the saws fit snugly when you slide them on, try a few different slitting saws. Then turn the arbor in the 4J making sure it is centered and then drill and bore the arbor to except the cap, that determines the concentricity not the cap. The reason for the wave washer under the bolt is so the cap doesn't keep tightening until you cannot remove the bolt or it breaks. It is not going to loosen. If using larger slitting saws then one may want to add a keyway. At the end of the day most slitting saws may not be absolutely concentric, the arbor was withing 0.001" TIR, much better than many slitting saws or for that matter the collet holding it.

20170409_174128.jpg
 
Wow, lots of opinions! And ways to do it.

@JimDawson is that just a carbide router bit? Just put it in a boring bar holder? Hmm, I could grind a lathe tool for this. That might be nice.

I have a hair over 12" of 1144. Enough to do 2 arbors. (More like a second chance, if I mess up in my first attempt!) But if I cut the 1144 into 6" pieces, there's not much of the cap to hold onto, once it has been cut off. Just maybe 0.30", which is hard to get right, or at least it is for me. Maybe worrying about nothing. Guess I'm going to have to wing it. Still going with @mksj 's basic design. I like it.
 
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