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Monday, June 21, 2010

Rebuilding a Powermatic-71 tablesaw




 I couldn't believe my eyes, but there it was in  Craigslist Tools for sale:  Powermatic saw  $100.

It must be a mistake or a terrible mess of a great old machine.  It was at least worth the trouble to go look at it, but I was doubtful of the outcome.


It had been used for years by the same folks, and had just become an albatross...it didn't start and looked ugly...so just get the 300 pounds of iron out of my shop.  They loaded her on my trailer, accepted my 5 Andy Jacksons and away I went.


looks nasty
It is SN 1-4747, manufactured in 1960, and had been used in a local millwork shop--wasn't rusted at all.  The top is beautiful and includes three solid cast wing sections.  There also is a Biesmeyer overhead blade guard and a Biesmeyer  rip fence, but no rails. I'm not sure if it will be worth it to get the fence fixed up.  The rest of the cabinet and the fence are beat up and nasty from years of hard work.

Initial problems appear to include non-starting motor, attachment for blade elevation screw, and some aesthetics.    Since it only cost $100, I think I will be money ahead to just buy a new 2HP Baldor motor, clean her up a bit and put her back to work.

Couldn't find drawings for the Model 71, but did find them for the 70 and 72.  It looks like the 70 has same construction as mine, but the 72 switched from the screw mechanism to a worm gear for the blade adjustments.

After pulling the motor and flipping the saw over, all I see is the blade lift-screw issue,  but the rest seems OK. 

...........
Wednesday 6/22:

Well, thanks to terrific machining by Powermatic, nothing is wrong other than decades of pitchy sawdust buildup.  She probably had been relegated to ripping pine for their windows and doors.  When I took it all apart, I found the blade lift assembly choked up with debris.  Nothing wrong with the screw or u-joints.
Blade lift assembly


I love well built machines.  This is going to be a great project.

I gave the folks from whom I purchased it a call, and asked if maybe the rails for the Biesmeyer fence were still around...Yippee, they are.   Chances are, I won't even have to buy a fence.

Friday 6/25:
50 in. Biesmeyer fence system intact.  That is a $400 relief. It will need a coat of paint to look pretty, but it's in good shape.   I will replace the battered ply and formica faces on the fence, for accuracy and ease of use.   No reason to use plastic T-mold like the orig...made cherry edges on the 1/2 in. drawer stock plywood.

beat up fence

The problem with the old motor might be build-up of sawdust.  The electrical tech  suggested I can save myself $500 by cleaning the contacts.   The caps were a little weak, according to him, so if I can get the bugger to fire, I'll replace them and be good for another 20 years.

Opened the motor case and blew out any dust (not much in a sealed case) and the contacts were shiny.  Put it all back together and rewired it to take back to shop for testing.  If it fires, great, if not, a new motor would not hurt my feelings.  I figure I'm still about $1900 to the good.

Got the saw cleaned and back together. Ready for the motor.  Look at that screw assembly -- 50 years and no rust!  Wish I could say the same for me.

reinstalled blade lift and screw


Monday 6/28 : Gee, this story just keeps gettin' better.   Motor checked out fine.  It is a bad switch.  I didn't even have to buy capacitors.   Sure glad I didn't have to get a motor...the price was twice what I imagined -- $700-$900!   Left $20 in the Electric shop pizza fund, since they were so helpful.  Can't wait to get a switch and a 12 in blade, and fire this baby up.

Naturally, a 220 switch can't be found in Anchorage. ;o(    Ordered one from Grizzly -- got soaked on shipping, so cost me $80.  

new fence faces and paint job 

July 10... Switch arrived and I wired the saw, new outlet on wall and a 25 ft extension.   She sounds wonderful !   All square and true to the table. Bies fence re-faced.  Original used plywood with formica face....I'll try that because UHMW is just too darned expensive.   A few things to do yet, but I'm happy to say it cuts like you would expect a fine saw to do...and looks pretty sweet as well.





new turned handles, new switch  and paint job for cabinet

The Powermatic takes its place with a Unisaw in my shop to start the kitchen job.  I think the woodshop angel is taking good care of me.



A little wrinkle...I noticed that although I have the fence parallel to the blade, the blade isn't perfectly square to the table.   I was home sick, and bored, so I took the saw apart and worked on the half-moon trunnion adjustments.  One of the four set screws that allow adjustment for the trunnions was broken off, so after about an hour of screwing around with it (literally)  got it replaced.  Unfortunately, maybe because I'm sick and not thinking straight it never got back to square.
 From the image above, you can just pick out the trunnions and the adjustment post/set screw.


I guess I will take the next opportunity to use some down time and take it apart again...a rather strenuous undertaking.   A tip I figured out:

To remove/reinstall the motor to the motor plate, just get it lifted up and clamp with squeeze clamps.   Then getting the four attachment bolts on is easy-squeezy.   Except things slipped an the motor dropped on my chest and popped an intercostal I think.  Hurts like hell.   Anyway all square again and ready for sale.





4 comments:

John Watkins said...

I paid $120 for the same saw just recently, but without a motor.

Your post here gives me hope that I can get the Raise-Lower mechanism working again (mine had broken at the universal joint)... and that the end result will be worth keeping.

Regards,
John

RAHUL SHARMA said...

Thanks for Sharing your valuable Information. I really like this post.

Rick said...

Any idea what rpm is recommended for the motor? Mine has 3 phase motor which im changing out. The motor tag is missing so I dont have a lot of knowledge about the motor.

Rick said...

Any idea what rpm is recommended for the motor? Mine has 3 phase motor which im changing out. The motor tag is missing so I dont have a lot of knowledge about the motor.