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View Full Version : Saw arbor jam-up prevention?



J Tiers
12-11-2010, 10:58 PM
Any clever ideas for prevention of saw jam-up on the spring-loaded multi-size arbors?

Yes, making a dedicated arbor for each size, possibly with key pin, would probably be a good idea..... I haven't done it, and don't want to at present.

I have, however, had saws get tightened so much that the cap screw could not be removed. The only way I have loosened them was by gripping and turning the arbor 'cap" with large pump pliers while holding the saw blade securely, with the whole works off the mill.

There has to be a better way..... I was thinking of making a new cap with wrench flats, or that plus flats on the shank assembly....or adding a washer that has wrench flates, as is sometimes used on holesaw mandrels.

At some point new arbors starts to get sensible, but at least the solutions would work for several sizes of saw with one part made, if I stick with the multi-hole arbor as a base.

the last time, the saw dug in so hard that the keyway raised a burr on the arbor... which probably toasted this one anyhow.....

http://img.photobucket.com/albums/0803/jstanley/saw_arbor.jpg

beanbag
12-11-2010, 11:08 PM
Your arbor isn't toasted at all. Put it on the lathe and trim off that burr. It will probably be better than new.

I would definitely not want any strong blade locking on my slitting saw since that would immediately shatter the blade if it got caught. I would rather have it spin a few turns.

macona
12-11-2010, 11:10 PM
I wonder if you could put a touch of lapping compound on the arbor surface where it seats on it. This would keep the saw from spinning and tightening the screw.

oldtiffie
12-12-2010, 12:43 AM
Just as well you are using it so the nut tightens JT else the cutter would stop with power feed on as the nut was loosened.

There are two, possibly three or four problems:
1). the cutter/saw is "wandering off-line";

2). the gullets of the teeth are too small and too shallow and swarf is building up and jambing between the cuter side faces and the job side faces as well from the point of entry to the whole lengths of the sides of the saw cut;

3). the saw outside diameter is too large;and

4). there is no driving key - or cheek-plates.

The driving key (1/4" square) will stop the nut moving and either tightening or loosening.

I will post the solutions later in the day.

oldtiffie
12-12-2010, 04:31 AM
First of all, most or many slitting saws are too flexible due to their large diameters. The solution is to use the smallest diameter available and/or use side/cheek plates as on many grinders.

Those thin cutters DO tend to wander off if the original cut is set too deep - so take a shallow first cut and it will act as a guide for the follow-up cuts.

Here is a good item on it from "Machine Shop Trade Secrets" (Harvey) USA:
http://i200.photobucket.com/albums/aa294/oldtiffie/HF-45%20Mill%20misc/Slit_saw1.jpg

Next, I always use a drive key - through the cutter (face/cheek-plates too - if any) as it saves the cutter, prevents nut "lock-up" or loosening and reduces scoring on the arbor which can make it very difficult to remove cutters and spacers from the arbor and I always and only use genuine key-steel keys.

Next, if necessary, I remove at least half the teeth to give the swarf more chance to avoid compacting and being forced between the sides of the cutter and the slot being cut.

Cutting fluid is preferable to cutting oil as it is more likely to flush out at least part of the swarf whereas cutting oil being "sticky" tends to retain and pack the swarf.

Cutting or slitting saws are not as good as side-and-face cutters (the "staggered" variety being better than the "straight" variety). That is to say that they do not have any "set" and are not wider than the centre disk whereas side and face cutters and cutters with silver-soldered TC tooth tips do.

Here are a couple of pics of my MT3 arbor with a side and face cutter and a slitting saw.

http://i200.photobucket.com/albums/aa294/oldtiffie/HF-45%20Mill%20misc/Stub_arbor1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/HF-45%20Mill%20misc/Stub_arbor2.jpg

Rosco-P
12-12-2010, 09:21 AM
After turning or grinding off the burr, why not mill two flats on the arbor flange, so you could hold it in a vise when removing a stuck blade? Or quick and easy, a hole for a pin spaner.

J Tiers
12-12-2010, 10:18 AM
Your arbor isn't toasted at all. Put it on the lathe and trim off that burr. It will probably be better than new.


Done long ago..... trimmed off the damage until the surface stopped "winking".... the arbor was hardened, it was harder than I thought.

But the arbor is slightly bent, even though the saw will run true since the trimming..... it 'fits" into the holder a bit tight now, I probably ought to replace it.

BTW, you can't trim much off these, since the spring-loaded stepped centering cone is apparently trapped by a "spun-in" overhang on the inside of the arbor itself. If you need to trim much, you will cut into or entirely remove the slight overhang, and the centering cone will be free. Still usable, but a lot more hassle.

I was hoping someone had come up with a reasonable way of keeping this type arbor from tightening excessively.....

Unfortunately, the basic design does not lend itself to much other than adding washers, in the hope that they will spin first, and save the 'cap" portion from spinning and tightening the screw.

The answer is to make a few better arbors..... with key pins. That stops the spinning, usually (see below).

Rosco: ....... yes, I have considered flats for removal, as I mentioned in the original post.... that still takes a lot of force to remove.... I am thinking that a flatted washer as used with holesaws is a possible plan, but is not particularly compatible with that type arbor, which is otherwise quite convenient.

Turning the flatted washer usually loosens the holesaw with little effort, and it might work on these also.... holesaws suffer from direct force tightening them onto the arbor. The screw here is tightened as the 'cap" portion spins, which can also spin the screw.



Tiffie:

honestly you ought really t read the posts before writing a treatise.... it isn't as if we don't appreciate the effort, but many of your points were actually either explained or mentioned as solutions already.

it's a horizontal mill, although being used as a "vertical" right now (w/o overarm used), and I am very well supplied with keyed arbors from 0.875 to 1.25".

A key is no guarantee of goodness.... this one got cut halfway through, could easily have finished the job. And the saw that did it was about 3.5mm wide.

http://img.photobucket.com/albums/0803/jstanley/cutkey.jpg

S_J_H
12-12-2010, 10:35 AM
I have had pretty good results using a expanding arbor to hold my slitting/slotting saws.

You get the radial holding force from the expanding ID and the holding forces from face to face.
I really like the HSS slotting saws. I have had this 2.5" ID -3/32" thick saw blade for a long time and it is still razor sharp.
http://i109.photobucket.com/albums/n48/S_J_H/1978%20kz650/IMG_0057.jpg
Steve

J Tiers
12-12-2010, 02:53 PM
That's an interesting idea.

But I have not seen anything like it, did you make it?

oldtiffie
12-12-2010, 03:09 PM
JT.

Did you notice that S-J-H (Steve) was using a side and face cutter - and not a slitting saw?

http://i109.photobucket.com/albums/n48/S_J_H/1978%20kz650/IMG_0057.jpg

A S&F cutter is pretty well self-cleaning as regards the sides, has plenty of "gullet" and will not or is a lot less inclined to "wander off" and because it is relatively thick is a lot "stiffer".

My original suggestion of a shallow preliminary cuts stands - if you must use slitting (thin) saws.

J Tiers
12-12-2010, 09:03 PM
JT.

Did you notice that S-J-H (Steve) was using a side and face cutter - and not a slitting saw?


A S&F cutter is pretty well self-cleaning as regards the sides, has plenty of "gullet" and will not or is a lot less inclined to "wander off" and because it is relatively thick is a lot "stiffer".

My original suggestion of a shallow preliminary cuts stands - if you must use slitting (thin) saws.

yes I did........

and I was not, in this particular instance, cutting a deep slot.... so the problem didn't arise. The "shallow preliminary cut" was the final one.