Blade wobble Two Machines Same Problem

[StevenAyres]

I'm not saying I know what the answer is, but I notice that no one has yet mentioned the possibility of play in the arbor mount. If the bore is larger than the spindle diameter, the setscrew will pull the arbor a little off center, possibly at a slight angle.

The fit of the spindle should be tight enough that when mounting a chuck, you get some air resistance before it will push all the way on the spindle.

I was mounting a new blade on my brownie this weekend, and noticed the sort of symptom described in the OP. I took it down again and flatted the spacers, making sure they were really clean on all bearing faces. It helped. I don't expect this is the answer here, either, but it's a tip to keep in mind.

[Hobbyman2]

I had the exact same experience when I got my'n , here is what I did with the process of elimination, first I checked the blade for flatness , laid it on a flat surface , a table from a table saw will usually be god enough, maybe a work bench , a machined piece of granite is what I used , but they are not cheap . next step is to put a bit in a drill chuck and check to see if it starts perfectly or if the tip cuts in a orbital manner, if it doesn't check for run out on the main shaft , if it spins true then the last thing in the system wold be the arbor ? I can tell you that I went with the double bearing quill and it has made a huge difference in the shaft movement , however when I tighten the arbor to the quill it does add a small amount of distortion to the blade cut , I assume that is normal do to a .000 or so in the arbor its self , it will not be as accurate as a blade attached directly to a shaft as on a dedicated table saw . I have a question that may or may not be related , does the hight of the blade change any when it spins?
unplug it , install a blade set the depth of cut , slowly turn the blade . does the hight stay the same ? is there any variation in the height of the teeth ? I ask this because any thing that can alter the balance of the blade will change its performance just like a car tire ? Good luck ,don't give up , I set my mkv into thee lathe position , set the center point to point , spin the shaft , the centers should stay point to point on a precision machine .

Good luck

[JPG]

A 'perfectly' flat blade is elusive.

I have not seen a number that would reveal the amount of 'wobble'.

Same problem with two different machines MAY indicate a setup problem with both.

Are you both centering the set screw on the quill shaft flat by rocking the arbor rotationaly to place the set screw at the lowest point on the shaft?

The sanding disk MAY provide clues, but they are not perfectly flat either.

Also are there burrs on the quill shaft. Look at the edges of the flat.

[wa2crk]

Do you have a friend who has a table saw that is not a Shopsmith. If you do take your best blade and try it in his table saw. If it runs true, then the problem has to be in the arbor. When you loosen the set screw on the arbor you should hear a "pop" when the arbor comes off the quill shaft.
Is the arbor and the arbor nut machined true or is the nut machined at an angle from one side to the other.(different thicknesses) Do you have a universal work arbor to mount the blade to. If so mount the blade to one of the universal arbors. If you have the shaper arbor it would be a good one to use. Mount the blade to see if still has the wobble but DO NOT USE THE UNIVERSAL ARBOR AND BLADE TO CUT ANY STOCK!!. You are just checking to see if the blade runs true. What is confusing to me is that when you mount the drill chuck and drill holes the drilling runs true. At this point I would check the diameter of the hole in the arbor that the quill goes into and see if there is any play or wobble before you tighten the set screw. If there is then the arbor is still suspect. Also check to see if the hole in the arbor is machined at a right angle to the plane of the blade.
Bill V

[Hobbyman2]

I would think the pressure washers would absorb any distortion in the threads? am I incorrect ?

[reible]

How about a movie of the blade doing its wobble?

My guess is that what you are seeing is the result of harmonic vibration. I would make sure the quill lock is tight, the head stock lock is tight and the machine is setting on the floor.

Blades especially cheaper ones are not going to be all that flat. The more expensive blades will be better but then even they will be off by a couple of thousands(.002'-.003") And the teeth angles will also effect what you see as the blade is in transition. The best blade to view would be a rip blade with flat ground teeth, all others could be playing tricks on your eyes.

Dusty suggestion is good if the machine is in perfect alignment, the kerf should be really close to the blade width but make sure you are using the miter gauge and have it set right for a straight cross cut.

Gut feeling is that you really don't have a problem but if you want to do some more testing then we need to start using some scientific principles. I would also not rule out a bent quill shaft, new bearing with a bent shaft is still a bent shaft.

The easy way to test the shaft is to move the arbor and blade to the other end of the headstock. DONOT run the blade there but you can do some measurements to see if it is better there on another shaft. If it is then it would point to a bent shaft.

If nothing changes then move back to the proper location and we can do some more testing there:

Mark the arbor, and the blade and if you have a gauge take readings 90 degrees apart around the blade out near the rim of the blade for a fixed location on the main table. Loosen the blade and rotate just the blade about half way round (180 degrees) and tighten. Now repeat the measurements. It should be clear if the numbers are following the blade or the arbor/headstock. If you don't have a good gauge for this then we can go another way but this would be instructive.

Enough for tonight.

Ed

[Hobbyman2]

One way to find out is to make a cut then measure the width of that cut with a shim or something that is accurate.

I also wonder if the blade deviates when under cutting pressure ? my'n did ,it was impossible to make a accurate dado cut .

Using the miter gage and hex wrench or a mic set to the blade face use a piece of stock and push against the blade and watch for movement ?

If the blade doesn't cut properly it can be a issue with blade burning and kick back.
What has me concerned is a new machine " MKVII PP"doing this as well, that leads me to believe the issue is in the arbor,, at least on the MKVII PP ???

JMO

[billdvorak]

I have been using a cheap dial gauge. I use it for the fence every time and blade and table sometimes. I get very consistent results and measurements the bare arbor around .002 out.

[billdvorak]

Yes on kickback and burning with new blade and arbor

[billdvorak]

I’m the new guy in case it isn’t obvious. I will try to get a video of the wobble if someone can tell me how to post it.