NEW! Faster Search Option

Loading

Powermatic 64A Fatal Flaw

Dan58's picture

Hi All,
I've discoverd why my Powermatic 64A contractor saw has made such horrible cuts for the last five years.  I thought 'hey, it's just a contractor saw its not supposed to do any better'.  When I finally got a dial inidcator I found that the blade will not stay parallel to the miter slots.  Normal use will slowly vibrate it out of true and tilting the blade immediately takes it way out of whack and it stays out of whack when the blade is set back to vertical.  With a dial indicator the blade can be tweaked back to parallel by pulling or pushing on the splitter bar (which is attached to the carriage) after a few tries.  Unfortunately this needs to be done often to keep the blade running true.


At first I thought the issue was due to inadequtely tightened bolts that hold the carriage assembly to the underside of the tabel.  I tightened to the point of nearly stripping or breaking them but the problem still occurred.  I communicated via e-mail with Powermatic tech support and they sent an adjustment procedure that shows how to set the two main rails of the carraige assembly to be parallel and lock them down.  This pointed out the real problem.  The round rails that connect the front and rear trunnion pieces can rotate and twist under torque.  With the blade vertical the motor puts only slight torque on the assembly but at 45deg the weight of the motor twists the carriage rails considerably.  Trouble is, regardless of how tight the lock nuts are made the rails still rotate in their holes and take the carriage out of true.  When I informed Powermatic of this they suggested I take it to a service center.  The service center obviously will not be able to fix this because it is just a poor design.  Powermatic does not have a redesigned carriage for this saw.  They also would not honor any knid of workmanship guarentee. 

I'm wondering if there are other 64A owners out there with similar experience.  I've designed a fix for this and am testing it.  I'd be glad to share it with other dissatisfied 64A owners once I know it works.


Dan

bd's picture

(post #100759, reply #1 of 12)

I bought a model 64 right before the 64A's came out. I haven't had any similar problems. Are you sure you're getting the alignment set in properly instead of just torquing things into alignment without locking them in? That wasn't clear from your description. I did have to adjust the alignment slightly on mine. It took quite a bit of leverage to get the trunnions to move even a slight amount. Holding them in position while tightening down on the lock screws was a frustrating exercise, but I haven't had any problems since then. You might look at getting a set of PALS (I'll see if I can find a link to post). They provide some screws to help make the adjustment process easier & more exact.

http://www.in-lineindustries.com/saw_pals.html


Edited 5/17/2007 8:15 am ET by bd

Dan58's picture

(post #100759, reply #3 of 12)

Thanks for the reply.


The issue I'm dealing with does not invlove alignment of the trunninons.  That is fairly straight forward although the PALS look like they would make it a little easier.  The two 22mm shafts that connect the front trunnion to the rear one are the weak link in the assembly.  The alignment procedure for those has you lay a flat plate on the shafts, loosen the lock nuts at the rear end, tweak the assembly so that the plate doesn't rock and tighten the lock nuts back down.  At least on my saw, those shafts can twist in their sockets no matter how tight the lock nuts are.  The shafts need to have a square mortise/tenon arrangement with set screws to prevent twisting.


So, does tilting the blade to 45deg throw the blade out of alignment on your saw?  Try this: reach under the back of the saw and grab the shaft that holds the splitter or the motor and give it a tug.  See if that doesn't throw the blade out of alignment.  


This is great to get another view on this.  Thanks for responding.


Dan

bd's picture

(post #100759, reply #7 of 12)

I can't run that test right now on my saw. The saw's in storage. Bought a Unisaw last year. But I do not ever recall having that problem.

It's probably a "contractor" style saw design problem, not just Powermatic's. Unfortunately, yours maybe just a little looser on the tolerances than others. If you look at Ian Kirby's book, "The Accurate Tablesaw", he recommends avoiding use of the tilt mechanism completely on contractor style tablesaws. Instead he recommends the building of jigs or sleds to cut bevels. That said, however, there are an awful lot of people out there w/ contractor's style saws that do incredible work.

MSS325's picture

(post #100759, reply #2 of 12)

I have a 64a with the PALS installed. I usually check and tweak the alignment once or twice a year and it's always within 3 of 4 thou. The PALS really make a big difference in aligning this saw. It was a bear without them.  

Knotscott's picture

(post #100759, reply #4 of 12)

Dan - I don't have a PM64, but have you considered putting a bolt through the rod to prevent twisting? I've heard rumor that some rods are indexed now to prevent the issue.

EdHarrow's picture

(post #100759, reply #5 of 12)

IIRC Forrest Girl had a similar problem, but I don't recollect what brand of saw, nor do I recollect the cure.

Knotscott's picture

(post #100759, reply #6 of 12)

I think FG is a Jet-setter.

southpaw57's picture

powermatic 64A blade alignment problems (post #100759, reply #8 of 12)

Yes, I am facing the same problem. it seems, no matter how I try to align the blade, it will not stay. i have used the saw for some 10 years and all of a sudden it starts burning the cuts, i checked the alignment and it was out about 1/32". nothing has happened to create this problem. any suggestions?

southpaw

HowardAcheson's picture

What you are describing is (post #100759, reply #9 of 12)

What you are describing is endemic to all contractor type saws.  If the support bars get out of the plane of the saw, tilting the blade will "rack" the trunnions and cause the blade to move out out of alignment.

Howie.........
whizbo's picture

I see the same issue (post #100759, reply #10 of 12)

DAN58,

You're not crazy, I see the same issue on my 64A.  I started seeeing burns on wood caused by the teeth on the exit side of the blade.  At first I tried to adjust the trunions to get the blade back to parallel.  That worked for a bit, but the saw would still move out of parallel.  So I installed a set of pals like bd mentioned in his reply to your post.  I quickly used up all of the slot in the trunions, and the blade was still out of parallel.  The thing that made me start to suspect the saw was when I installed a zero clearance insert.  The problem became very apparent when the blade slot width started to grow.  The blade position is not repeatable!

At this point I've resorted to putting a dial indicator on the blade after any adjustment to the blade angle.  Then it just takes a push or pull of the motor assembly to get things straight again.  I'm growing tired of the problem and I went hunting for a solution, which brought me here today.


You mentioned a fix that you were trying out, have you had any luck?

CharlieL's picture

Deleted (post #100759, reply #12 of 12)

Deleted

If you don't have the time to do it right the first time, when will you ever have the time to fix it ?

HowardAcheson's picture

The problem is that the (post #100759, reply #11 of 12)

The problem is that the trunnion bars are not in the same plane.  This occurs if you try to tilt the blade too hard against the tilt stop adjustment screw.

Proper adjustment affects bevel cuts and is indicated when there burning when making bevel cuts.

First go throught the alignment process following the steps below "TABLE SAW BLADE ALIGNMENT".

To check whether the trunnions need to be adjusted, tilt your blade fully to the 45 degree position until you get to the 45 degree stop.  Then crank the blade back to the 90 degree upright position.  Now again check the parallelism of the blade to the miter slot.  If  the blade is still parallel to the miter slot, declare victory.  If not, follow the process below from Delta to adjust them.  The process is the same for all Contractor Saws or Hybrids that have the trunnion assembly hanging from the table.

1. Remove the saw blade being sure it was at it fullest height.

2. Place a flat plate (or similar flat object) on top of the two tie-bars. (The size of the plate should be at least 6" by 8", and the flatter the better. A pane of glass works well.) Depress one corner of the plate and if it rocks, the tie-bars are not parallel. This must be corrected as it will affect the alignment of the blade.

3. Loosen the tie-bar locknuts located at the rear of the saw.

4. Grasp the motor bracket and move it left and/or right. Check the rocking of the flat plate and when it can no longer rock, the tie-bars are parallel...re-tighten the locknuts.

5. Remove the flat plate and re-install the sawblade.

6. Again perform the parallelism alignment process.

7. Before tightening the rear trunnion bolts, push forward on the rear trunnion bracket to allow the undercarriage to snugly fit between the two trunnions.

TABLE SAW BLADE ALIGNMENT


Here is the low tech, low cost way to align a tablesaw that I learned maybe forty years ago and use to teach to my students.

Make 3/4 x 3/4 x 12" hardwood stick. Drill a hole somewhat centered in one end and insert a brass #8 x 1" round head fine thread machine screw about half way. UNPLUG THE SAW.  Raise the blade completely up. Clamp this board in your miter gauge (if you determine that there is some slop in your slot to miter gauge, use a playing card to take up the slop) so the screw head just about touches the blade at the front. Now rotate the blade by hand and determine which tooth is the closest. Adjust the screw in or out until it just touches this tooth. Mark this tooth. Rotate the blade so the tooth is now at the back of the table and move the miter gauge/stick assembly to the back and see if it touches the marked tooth to the same extent. If it doesn't, adjust the trunnion (if a contractor saw) or the tabletop (if a cabinet saw) until it does.

For a contractor saw, first use a small c-clamp on the rear trunnion and cradle to keep the assembly from moving.  Then loosen the two rear trunnion bolts and one front trunnion bolt.  Slightly loosen the other front trunnion bolt and use a stick to tap the trunnion until the blade and screw lightly touch.  The blade does not move directly around the center so you will need to repeatedly go back to the front of the blade, readjust the screw, and then again measure the back. Be sure to check after tightening the trunnion as the trunnion frequently moves when being tightened.

For cabinet saws, loosen the bolts that hold the tabletop and tap one corner until things come into alignment.

The same adjustment gauge can be used to set the fence parallel to the miter slot.  Slide the miter gauge to the front of the table and move the fence over to the screw head and insert a playing card between the screw head and the fence just so you can move the card as it touches both the fence and the screw head.  Now move the miter gauge to the back of the table and see if you have the same feel when you insert the card.  I like my fence absolutely parallel--if you want to have a slight opening to the fence, you can easily estimate the opening by adding a thickness of paper to the card.

I always show my students with a dial gauge that their adjustments are within .001 - .002.

You can also use the same gauge to measure blade runout by using a $5.00 feeler gauge.

Finally, after you are satisfied with the above adjustments, check the position of the splitter to make sure it is exactly in line with the blade.

Bottom line, there is no need to spend more than the $0.05 for the brass screw.

Howie.........