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Planer Bed Flattening Using Hand Scraping

Blademade

Plastic
Joined
Aug 12, 2021
Hello! This is my first post on the forum and I’m happy to hear all of your thoughts

I recently bought a used Powermatic 100 planer that was built in 1960. It appears to have served a busy former life and there is a fairly uniform dip in the infeed, outfeed and Center bed sections of between 0.004 to almost 0.006. From my research so far, I’m led to believe that those tolerances would probably not be an issue for a woodworking application, nevertheless I have always been interested in the art of hand scraping and was wondering whether this could be a candidate. As I’m sure some of you already know, the thought of restoring quality machinery to its former glory can be a fun pursuit.

I was considering getting either a 12”x9”x3” or an 18”x12”x3” granite surface plate off of Amazon as they seem to be a great value with good reviews and accurate to 0.001. Would one size be more advantageous than the other in this application?, Other than that I also wouldn’t be opposed to buying a good carbide scraper.

I also plan to upgrade to a byrd shelix helical cutterhead for the unit as part of my restoration.

Any thoughts on this approach as a means of flattening the tables?
 
No expert but I'd think it was completely doable and the end result would be beautiful. That said, it's way beyond my arthritis and a power scraper would be the bee's knees. It's for wood so I'd think any decent reference surface would suffice. I'd want something moderately long and narrow, bringing it to the part, rather than a big surface plate. @Richard King will know far more about the best way.
 
I've done it and posted the pictures.

Steel bed on the 25" Ramco widebelt. Probably .050 wear channel. Maybe more 'til flat.
I ground a Powermatic bed for a friend, it had not only wear, but had had a wreck when someone in shop class turned it on without the knives being tightened. That was probably somewhat more than 1/16".

Due to the way the machines are built, it was faster to scrape the Ramco, (though it took a couple days) than to take it apart, schlep to a grinding house, go back and get it, and re-erect the machine.

AFA the Powermatic, at the time of surface grinding the friend's machine i did not have a metal planer; but do now.
That is the obvious machine for the job.

If you plan more than cosmetics, get a Biax, and it is very do-able.
I would buy the larger surace plate.
You will need some scraped flats or straigth edge to spot near the rails on the planer bed. Which is where most of the material will need removed, anyway. Granite surface plates have almost a 1/2" bullnose on the edges. Even 1'4" is too much and will cause you problems.
Perhaps get the granite, and buy a cheap old cast iron plate, scrape it to the granite, and use to spot the planer bed.

Anyway, a metal planer or large shaper would be the ideal machine to shape up your wood planer bed. Then scrape to refine if it floats your boat. Or plane to the German DIN standard for surface finish on machine tool tables, and stone after planing.

PS: This type scraping for metal removal is not small flakes & delicate touch. It is digging in with your thigh on the handle (& get the extension handle for the biax if it is available), the biax bucking & grunting, and large, splintery chips hammering off like buckshot, spraying the opposite wall if you intend to make headway. However, it is absolutely do-able.

smt
 
Blademade - If you decide you want to puruse the idea of buying hand scraping materials, including a couple of carbide scrapers in VG condition, please PM me.

-Marty-
 
Thanks for all of your replies! Unfortunately I don’t think I’d be able to justify buying a biax or any tool that exceeded the price of a nice hand scraper for this project. I am not in a particular rush and I am a very patient person, so I don’t mind doing the work by hand if it is feasible.

As stated , it looks like most of my scraping would be on the outer edges of the table as wood rarely would have passed through the planer on those outer edges, so I’m assuming the actual number of square inches of hard work wouldn’t be enormous. I’ve included a picture of the unit below, I plan to fully disassembled it for a rebuild, so I will have full access to the table.

What size of surface plate would be suitable for “bringing to the beds” ? Bringing the big surface plate would be too heavy / ineffective ?
 
I'm almost 70 & starting to find i don't like lifting things that were easy a few years ago.
That said, i used a 12 x 18 for my portable stone, to lift on and off machines for spotting. You can check the weight, i think it's less than a bag of cement (80 lb)? Using smaller stuff is a nuisance when scraping areas. You will need the scraped flat/ straight edge for near the rails.

At the rails save yourself a lot of time and aggravation - use about a 16" or 18" industrial hacksaw blade, which cuts somewhat more than 1/16" wide. One with only 6 teeth or so. Grip it about mid-point with vise grips, and use it to saw down beside/flush with each rail. This channel should be below the finish depth of the surface, ultimately. It may even already exist on some machines because it is more practical to grind flat, to a relief.

I think you'll be successful.
But if you flag, i'm not that far south of you with a planer.

smt
 
This might be a silly question but how would I go about posting some pictures on here? I can’t seem to !
 
I've never scraped anything as large as your planer table, so take my advice accordingly.

Sounds like you have the time and inclination, so scraping might be ideal for you. The best thing about it is you can do a little each day at your own pace. Kinda like hand lapping a telescope lens. And it will make a great story for your woodworking friends!

I would be inclined to get the larger surface plate, it could be much more useful to you later on, especially if you enjoy it so much you want to scrape all your hand planes. I'd probably rig up a chain fall or come-a-long to lift and position the table on the plate for spotting. Save your energy and strength for the scraping.

Also, if you want to try it before making any investment, just grind the end of an old file to proper geometry and go at it on a spot you know will have to come down. That's what I used before I eventually got a carbide scraper.

PS - I firmly believe that it's worth reconditioning the table top if you want to get the best results from your machine. And the Shelix heads are great, especially if you work in highly figured wood.
 
Richard I completely agree, I have many other uses for a large granite plate, so I can definitely justify that purchase, a 12x18 would also fit absolutely perfectly on my planer bed which is 12 & 1/4” x 24” long, so I feel like I’d have a pretty great reference point to go from with limited risk if I take it slow on the outsides. Even the thought that each thousandth I take off the edges of the dish will make the surface 20% flatter is attractive, since I’m 5 thousandths out of flat. As mentioned above, a small plate would also be necessary on the edges since the granite plates have rounded edges (not sure where I will find one at a reasonable price). I’m in Canada so prices are all quite a bit higher on average.

I still can’t find a way to post pictures on here but I wanted to show everybody the groove down each length of the table that was referenced above as well, so I wouldn’t need to make my own grooves.
 
Sorry Doug , I was trying to find a way to delete the other thread, since I figured I would get more input on the general forum. Any advice ? I seem to be able to delete posts but not the thread.
 
Thanks for all of your replies! Unfortunately I don’t think I’d be able to justify buying a biax or any tool that exceeded the price of a nice hand scraper for this project.

My experience is that scraping is not a "DIY and save money" kind of hobby. Do you already have a carbide sharpener? Metrology tools?

.005" on a 12x24 surface is a LOT, and will take a very long time. Why not start on something small?
 
Scraping this much material over such a large surface I would say is an enormous job !
It would certainly be a way to get that final flatness you're looking for.
You might want to consider some form of electric sander to take down the high areas fairly quickly. Maybe a belt sander with an old dull belt, or an orbital sander.
Obviously you'll need to be very careful. Try it on a high area and carefully measure your progress.
I've cleaned up old woodworking machine surfaces with emery cloth attached to a piece of wood. I was not looking for the accuracy you're after, but it worked.
Bob
 
Here was a great response I got on the “other” thread I mistakenly started, which I’m having the moderator remove - oops!

“I assume you have or are going to dismantle the machine. As the mdl 100 is pretty numerous in all conditions I'd suggest posting on the OWWM site for a non worn donor table. You can of course have it machine shop surfaced. However, if your interest is in doing it your self it can be done quiet successfully with a hand sander and precision straight edge. Cast iron works much like hardwood only its not at all as pleasant to work, i.e. dirty for you and tools. Getting to a factory standard within 1-2K's can be achieved with a standard 5" random orbital and a 3' descent straight edge. Less than 1K will require more precision tools. Preferable a Festool or Bosh turbo 6" dual mode oscillating sander and a Starrett or Brown 3-4' straight edge with fine feeler gauge stock. Hook n loop abrasive is desired as you will be doing a lot of changing. And you'll want the best industrial abrasive, i.e. 3M Cubitron II. Most all your leveling work will be with 80 grit. The final surface finish is just dependent on your personal finish. Like flattening a work bench mark-sand-check-mark-sand-check. Change paper often-very often it wears fast. This is a tedious task as is bluing-scraping-checking-(lifting-flipping), but much faster though more obnoxious due to the flying metal dust. My method when truing large jointer tables 4'+ to less than 1k tolerance. For flat woodworking machine surfaces that are prone to surface corrosion and hard to treat and wax like thickness planer tables its preferable to have a smooth surface versus a flaked or planned surface more desirable for a large hand surfacer /jointer or band saw table.
~Warren”
 
My experience is that scraping is not a "DIY and save money" kind of hobby. Do you already have a carbide sharpener? Metrology tools?

.005" on a 12x24 surface is a LOT, and will take a very long time. Why not start on something small?

I don’t have any of the required tools yet but I’m never against buying good tools if it makes sense to. In my case I’m wondering whether the orbital sander route would be the most sensible. The high spots on my planer bed are quite pronounced so I feel like even taking them down slightly as per Warren’s suggestion would almost cut my “dish” in half if I’m careful about it and check for flatness regularly?
 
Agree that assembling all the gack to scrape machinery takes time and decent amount of money. Don’t agree that five thou is all that much even by hand on a 12” x 24” surface. It’s a wood working tool- 3-4 points per inch would be plenty. Before I had a Biax I did two surface plates to 10 ppi with with roughly same depth holes as OP. I’ll admit, I did wait for the Biax to get them to 40 ppi. :-)

L7
 








 
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