PM66 blade wobble and flange runout

[Brad Ridgway]

I've been diappointed in some of my rips as well as sheet cutting lately. Some sporatic burn marks, the rip line isn't dead staight and the stock seems to pull away from the fence (toward blade) unless i use force / featherboard to push it against. I have aligned blade to slots and fence to slots (maybe out .002 at the exit to prevent binding) a couple of times to no avail. Not sure why i had never looked/paid attention before, but you can definately notice wobble on different blades wth the naked eye (especially while it's spinning down, but even if you turn by hand).

So i decided to look at the arbor / flange ...


1) the arbor runout is < .001 (as measured on the not threaded ortion right up against the flange). so we're good there...

2) I can't get my dial indicator rdirectly on the fange (i have a TS Alighner junior and the height / offset won't let me get low enough in the slot without be obtaining another arm type mount), but i did measure on the blade and on a forrest stiffner which is as close to dead flat as any reference i have. Anyway, ii took the measurements @ ~3" from center. Sure enough there are two extremes across the 360 degrees the difference being ~.01.


I'm positive this is my issue, now what can i do about it... If the arbor runout is nill, seems like the flange isn't perpendicular to it. I'm not totally sure how those things are manufactured, but can i bang "inwards" with a hammer and piece of wood towards the motor on at the point where it "pulls away" the most? Do i buy a replacement arbor (is it easy to swap out if i do)?

thx in advance
-brad

[David Christopher]

Brad, you can give it a tap or two to see if it will help but you have a dang nice machine and I would get a new arbor if thats what is needed...you can call PM and get answers to alot of questions that you will have.....I think if you do this the right way you will never be sorry

[John Thompson]

If you have checked what you mentioned.. are you running a splitter? If so.. I would check it's alignment first. I developed a slight burn the other day and with my normal check if that happens... the splitter had slightly bent to one side. I change blades about six time a day and the splitter gets taken off and on several times a day for non-through cuts also. As you know they are relatively thin and a bit flexy as it has happend more than once causing burn.

Just a thought before you get into the heavier issues.

Good luck...

Sarge..

[Paul Murphy]

I had pretty much the same issue you describe with arbor flange runout on my PM66. Mine was due to rough machine work on the flange face. I ordered a new arbor/bearing assembly from PM, and IIRC it was < $100 with shipping.

The arbor assembly is fairly easy to put in, and is secured in the lift arm by a setscrew. Be sure to check for blade clearance l&r of blade before tightening setscrew, especially @ 45 degrees. Also, if you have a cutoff sled or other similar jigs you might want to line the blade up to that cutline, otherwise all your fixed tape measures (and fence scale) will be off.

I didn't have to remove the saw top as PM suggests, but if you are cleaning up the mechanicals it would give easy access.

[Brad Ridgway]

Thx guys...

i do have the biesmeyer splitter, but i have the "pulling away" problem even without it (it's slight, but it's noticble).

Paul, just curious... if you didn't take the top off, did you have enough access from the blade hole? or crawl in from the front access door (i hope not!). I have to deal with the side, outfeed and slider disassembly so if i proceed taking the top off is not something i'm really keen on :)

thx
-brad

[Bruce Wrenn]

You could take the arbor out and have it turned between centers to straighten up flange. Your machinest will know what you are talking about. It will take longer to set up lathe, than to true the face of the arbor. This is a good project for a student in a machine shop program. Lucky for me my neighbor has a machine shop in his garage, and I built him a rotary converter.

[Paul Murphy]

Thx guys...

i do have the biesmeyer splitter, but i have the "pulling away" problem even without it (it's slight, but it's noticble).

Paul, just curious... if you didn't take the top off, did you have enough access from the blade hole? or crawl in from the front access door (i hope not!). I have to deal with the side, outfeed and slider disassembly so if i proceed taking the top off is not something i'm really keen on :)

thx
-brad

Brad, I took the motor cover off to remove the pulley, and went through the blade access hole in the top to do the rest. If you don't drop any parts or tools there is no need to go through the front access door. It isn't too bad of a job.

[Peter Quinn]

Brad, I had a similar problem with my PM66 a few years back. There is retainer clip, a weird two piece thing, not a C clip, that sits behind the pulley on the motor side of the saw arbor. This retainer clip is subject to failure on occasion. I found mine in the bottom of the cabinet on accident after I noticed what appeared to be serious and sudden performance issues like you note. I called WMH service, they said this happens at a clip of about 5 calls per year, I know of at least two other creekers that have had the same issue.

I don't KNOW that this is your problem, but it is easy to check. Pull the motor cover, pull the motor, remove the drive pulley, there is a slot in the shaft in which there should be a retainer clip, it is the last thing in line before the shaft passes through the bearings. I found half of mine on the cabinet floor, the other half still on the shaft but not doing its job. If its off, the blade moves in and out a bit during a cut. Spin it by hand and it seems fine with an indicator, fire it up with a blade on it and push wood through it, not so fine. I replaced that silly two piece clip with a C clip as advised by others with the same problem, end of problem. I had to mic the shaft and clip with calipers to determine which size clip to get as WMH would or could not tell me and offered to send me the same clip as a replacement. Why would I want to replace a bad design with the same bad design?

[Brad Ridgway]

Peter,

guess i'm a graphical guy and would rather not pull the motor (that 5hp was beast to even twist to tighten the belts). unless i know exactly what i'm after..

i am guessing you're referring to the outer #53 and maybe #64 in the diagram (page 26) in the manual?

http://content.powermatic.com/manuals/man_1660750K.pdf (http://content.powermatic.com/manuals/man_1660750K.pdf)

-brad

[Peter Quinn]

Brad, I may have been confused as its been a while, but it is actually part # 43 that fails. It holds the shaft that holds the arm that holds the arbor. It is directly behind the motor pulley. The motor with attached pulley must be removed to access or even view it, and I admit this is no great joy. It caused the entire assembly to begin shifting towards the fence under load, though exactly why doesn't seem clear to me now looking at the diagram. I'll never forget seeing the blade begin to drift towards the fence a bit during a cut, that got my attention fast.

[george wilson]

If I had that runout problem,I would take a large hand held grinder,and CAREFULLY apply it to the face of the arbor when it is running. The arbor flanges are usually dished in the middle,so only about 3/8" touches the blade.

I am also a machinist,and have used this technique years ago,before I had any lathe,to grind down a 6" fine tooth HSS blade to .020" kerf for cutting guitar fret slots. I have used it since about 1963.

You need to brace the grinder,and not let it follow the undulations of the arbor flange as you grind its face down. Also,do not grind the flange convex. There is probably only a few thousanths of runout at the flange,which gets multiplied as it approaches the 10" diameter of the saw blade. Wear protective face gear,and don't run the dust collector while doing this. Clean out the saw first,to avoid slow,smouldering fires in the sawdust.

[Tom Henderson2]

If I had that runout problem,I would take a large hand held grinder,and CAREFULLY apply it to the face of the arbor when it is running. The arbor flanges are usually dished in the middle,so only about 3/8" touches the blade.

I have no doubt that you could do this successfully George.

But for most of us it would be a disaster....

-TH

[Brad Ridgway]

FYI - as some of of you may have seen in my panic post on the pulley i got my assembly from PM today and started on this tonight...

Peter - i rulled out your issue (at least as the main cause) because i have the wobble even with the belt removed, so it was in the arbor...

Paul - you were spot on. I put in the new one and all i can say is wow. No wobble (at least not that i can detect with the naked eye. I haven't tightened the spacer set screw yet, but i put a dial indicator and in stead of being out .01+ (or more), looks like i'll be out maybe .002 about an inch in from the edge of the blade (and of course some of that may be the blade. I'm so excited - cuts without burns - here i come!!!


Two more questions for you... my old assembly was mounted almost to the edge of the blade side of the "raceway". I assume this isn't critical? but i have ~.25 inches on the other side...

and lastly, if you didn't take your top off , you have any tips on how you alligned the pulleys? I'm guessing just stick your head in the motor hole with a striaght edge?

thx
-brad

[Chip Lindley]

1. Does make a difference where the arbor flange ends up. The blade must be centered in the table insert at both 90 deg. and 45 deg. Otherwise there would be no issue.

2. Rather than trying tedious alignment beneath the table, install the arbor pulley and key without tightening. Install the belts. Tighten the motor support for belt tension. Jog the motor, to run a few seconds at a time. The belts will help to *self-center* the arbor pulley. Do this until you find the *sweet spot*! THEN, you can check alignment between the two pulleys with a straight edge to see how close *good-enough* really is!