Slitting saw arbor - Disappointing

[WobblyHand]

The Sierra American 1" arbor uses a 5/16"-18 thread. Just turn down the head of the screw. Takes a minute of your time and it is done. Also chamfer the back side of the screw head to remove any burrs from the turning. Then you can get on with life.

This assumes that the only thing wrong is the screw hole is off center.

If you bought this arbor from McMaster, please send them a note that your arbor is made incorrectly. They will offer to send you another one. It will also probably off center. Mine was. You can also send a note to Sierra American. If you don't tell them something is wrong -- they will never know. Sierra American has a quality problem which they don't seem to be acknowledging. Perhaps more reports will get them to realize there is a problem, at least with the lot that they shipped to McMaster. The issue is they are drilling the hole in the wrong place, which tells me their drilling fixture has an offset problem... Or their counterbores are way too tight!

 

[Just for fun]

You stated .011 clearance between the cap and the bore of the arbor. That is your problem. It is the registration of the cap to the arbor and the cap to the blade that will determine the ultimate possible run out. If that clearance is nice and tight like it is supposed to be then it is unlikely the bolt can pull the cap off center. The bolt should NOT be able to have an effect on the run out. But you also do not want it to be trying to pull it off center either or that will insure that it is always at max run out possible. If everything is correct the ONLY part of the bolt that should ever touch the cap is the bearing surface on the bottom of the head. Neither the shank nor the sides of the head should touch the cap when tight.

We already know that the cap dia is way to small for the arbor bore. Measure the cap dia to the saw dia. it should be a very close fit, That will tell you if it is the cap or the arbor that is made wrong.

It's a little sloppy also in my option. I tightened the cap up on the arbor backwards with the arbor still chucked up in the ER40 collet so the cap would not move, with my hand the most I could get was .004.

 

[woodchucker]

not sure why you would go down the same path as Wobblyhand and expect a different result.
you know what Einstein said...

I don't buy arbors, I always make my own. Way less money, wayyyy better results.

 

[Just for fun]

The Sierra American 1" arbor uses a 5/16"-18 thread. Just turn down the head of the screw. Takes a minute of your time and it is done. Also chamfer the back side of the screw head to remove any burrs from the turning. Then you can get on with life.

This assumes that the only thing wrong is the screw hole is off center.

If you bought this arbor from McMaster, please send them a note that your arbor is made incorrectly. They will offer to send you another one. It will also probably off center. Mine was. You can also send a note to Sierra American. If you don't tell them something is wrong -- they will never know. Sierra American has a quality problem which they don't seem to be acknowledging. Perhaps more reports will get them to realize there is a problem, at least with the lot that they shipped to McMaster. The issue is they are drilling the hole in the wrong place, which tells me their drilling fixture has an offset problem... Or their counterbores are way too tight!

I did buy it from McMaster-Carr. Turning down the bolt would allow me to center the saw but not really solve the problem.

If they don't refund my money, I will turn down the bold and go from there. I wonder if I could weld some Silicon Bronze strips on the inside of the arbor and then bore it to the right size?

Ultimately, I will make my own as others have said.

 

[Just for fun]

not sure why you would go down the same path as Wobblyhand and expect a different result.
you know what Einstein said...

I don't buy arbors, I always make my own. Way less money, wayyyy better results.

Well, If I would have did more research before buying, I would have went a different route.

I guess I just didn't have my confidents build up to the point that I thought I could successfully build one to the tolerance I would like. But after seeing the poor fit of the one I bought and what I expected. I have nothing to lose and a lot to gain by making my own.

 

[WobblyHand]

It's a little sloppy also in my option. I tightened the cap up on the arbor backwards with the arbor still chucked up in the ER40 collet so the cap would not move, with my hand the most I could get was .004.

It's true that the cap isn't a very tight sliding fit to the arbor. Honestly, I don't think it matters. Are your saw blade teeth concentric to within 0.001"? I doubt it. Guarantee you my 28T Grizzly saw blade for $8 isn't that good. Nor my Malco blade that I got from McMaster. The cap diameter is a very good fit to the blade. And the TIR of the arbor face is quite low. I think that is good enough.

With my fix, the arbor is good enough for my work. The saw blades cut and track true and that's all I need.

Going through heroic efforts to fix the arbor when a simple solution is good enough, doesn't sound like a wise use of time. That's my opinion at this point, having gone through a very similar thought process as you.

Why go for a fancy, harder fix, if a simple solution is satisfactory? Do the simplest operation to make it work. For me, that was turning the head of the screw. I used a TCMT insert and it turned down a known good SHCS to diameter with no problem. There were no critical operations. That said, I'll make my next arbor. I did try that early on and failed. My bore had a taper so the cap failed to enter the bore completely. I think I have improved since then, so I am willing to try it again. However, I have a long list of projects that are ahead of the line, so it would be a while.

Please tell McMaster the arbor is made wrong. Make them put heat on Sierra American. If more people report it, maybe they will fix the problem. I really don't want to see any company go down the drain, even Sierra American.

 

[epanzella]

I had the same prob so I made my own. I never liked the idea of a cap screw so I retain my blade with a one piece shoulder bolt that locates the blade precisely and fits into a counterbore on the arbor body.

 

[Just for fun]

What is the last photo with the four screws?

 

[mksj]

If the cap is loose in the arbor it will always wobble. I would return it as defective, they will give you a refund. Some plans below for an arbor to fit a 3/4" collet that I designed a few years ago. You make the cap first to verify fitment to the blade hole, then bore the body to match the cap. I used O1 drill rod, but 1144 also works well. One of these days I may blue the arbor.

 

[Jim F]

What is the last photo with the four screws?

Looks like screws made from bolts.