Platen ideas

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Jun 3, 2017
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I just made a new platen and ground my first blade on it.
XsHO3XH.jpg


I have a little 1x42. The black L piece is the original platten. I am aware these cheap L plattens flex, but honestly before now my grinding skills were bad and i couldnt tell.

I made the new platten by welding 2 pieces of angle iron into an L shape. I invented some crazy clamp trickery to get it clamped perfectly square before welding and it came out straight as you could ever get angle iron. The vertical angle had a notch cut out to fit around the bottom piece, and i welded all 3 contacting edges.

I drilled some holes in the vertical piece and can bolt on various plates. These plates must be drilled and threaded to have a smooth face the belt rides against.

It came out pretty well but if i bear down on it it still flexes just a tad. Whereas the old platten might move 1/4" at the top, the new platten might twist just a barely noticeable amount. I honestly expected it to not move at all.

I am curious if anyone has a better platten for this kind of sander? I have read several "improvements" that dont actually have any back support. I figure even with a center back support, it might still twist a bit.
 
It would probably help if you posted more pictures of the matching with different angles. Specifically of the platen arrangement. Bigger is usually sturdier with grinders. So with that in mind you could try and do the same thing you have here, only with thicker angle iron. Perhaps 1/2” thick. Or, since you have a welder, try and rig something up with plate steel. Maybe like the KMG does, only smaller scale.
 
Not really a lot to show. The vertical piece is sitting on top of the bottom piece and all the welds are on the sides, no welds on the bottom. There is one bolt that secures it to the machine.

AwEqrbs.jpg


My welder struggles with 1/4" or thicker parts i have to grind the edges thinner and preheat. Welding 1/2" is not possible i believe. I will research KMG plattens and see if it is possible.
 
Well, i just took it off to paint it and there was caked up dust under it i never cleaned off. I cleaned it and bolted it back on and it is rock solid.... so nevermind i guess.
 
I just made a new platen and ground my first blade on it.
XsHO3XH.jpg


I have a little 1x42. The black L piece is the original platten. I am aware these cheap L plattens flex, but honestly before now my grinding skills were bad and i couldnt tell.

I made the new platten by welding 2 pieces of angle iron into an L shape. I invented some crazy clamp trickery to get it clamped perfectly square before welding and it came out straight as you could ever get angle iron. The vertical angle had a notch cut out to fit around the bottom piece, and i welded all 3 contacting edges.

I drilled some holes in the vertical piece and can bolt on various plates. These plates must be drilled and threaded to have a smooth face the belt rides against.

It came out pretty well but if i bear down on it it still flexes just a tad. Whereas the old platten might move 1/4" at the top, the new platten might twist just a barely noticeable amount. I honestly expected it to not move at all.

I am curious if anyone has a better platten for this kind of sander? I have read several "improvements" that dont actually have any back support. I figure even with a center back support, it might still twist a bit.
 
The original is in the trash can.

I ran into a little snag today. I use 1/8" hardened plate between the belt and the angle iron. I am making one knife that has a kick sticking out about 1/8" from the blade edge. So when i try to grind the edge up close to the kick, the kick hits the angle iron and i can quite get a smooth blade grind.

I finished this blade up with a file. Whenever i remake the hard plate, i will use 3/16". I also dont like kicks that stick out 1/8", but this was a use it or lose it kind of thing since i messed up a bit on the geometry trying a new design.
 
I make mine from 3/8" thick angle and they don't flex at all. I think it's easier to just make separate platens than to try to bolt on different faces to a single backer. Use JB weld if you want a hardened steel face.

MCC5gkph.jpg
 
I was in the mood to experiment some more with the platten. I wasnt liking what i had done since the platten backer was too wide and i couldnt grind down into a 90 degree notch. There were two ideas in this thread i liked, one was using t-bar and the other was using really thick angle.

I am going through an expensive divorce, so i thought i would do something without buying anything.

pG226BH.jpg

fIjOVGD.jpg


So i have 1/4" vertical bar bolted to a piece of angle iron that is bolted to the machine. Then i have a spacer and a welded piece of flat bar in a t-bar shape. This is a prototype, i will remake it. But i like it.

When i remake it, i will fix the issue i have with the nut rubbing up against the 1/4" bar, and also make it so i have some horizontal play, it is tight right now. I need to order steel here soon, and when i do i can get a piece of 1" t-bar and use it instead of welding flat bar together.

The platten is only 2", and i can easily resurface it as needed. I can also glue some leather to a piece of t-bar and have a leather platten. I kind of like the idea of having one major permananet holder piece and only having a 2" section of t-bar that is expendable.

I also need to make a new tool rest. The stock tool rest is now the major source of flex on this machine. I also really want to get rid of the plastic wheels.
 
Why you don t just reinforce original one ? Like this for example ...........If it is possible to use that bolt from down side , will be much easy....
qswkBQ8.jpg
 
Might be my old eyes, but it looks to me like the back end of your bottom angle is not touching anything??? Contact between your bit of angle iron and the body of the grinder looks to be pretty much just under that socket head mounting bolt. I would clean off the paint on the body of the grinder and then build up the back of the angle iron with your welder and grind it back as flat as you can using your original platen. Increase the contact and the whole thing might be more stable.
 
Natlek,
The angle iron i used is too wide, i didnt think it would matter, but then i found out it does. So i have to remake the whole thing.

RedFury,
Your eyes are correct. The machine has a raised portion around where the platten bolts on. I very could build up the bottom of the platten backer.
 
Alright. Remade the base so the nut wouldnt rub against the vertical bar, and also put the vertical bar on the other side so the horizontal bolts wouldnt rub against the table. I realized i had the washer between the machine and the table, so moved that washer to be between the table and the blue handle. This made the table lay against the machine with a lot more contact area and it is much more stable now. So i will keep the table. I got the courage to saw off the left part of the table so i can change belts without moving the table. All in all, it is much better. And it was all done with scrap.

u34nbJG.jpg
 
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