Improvising

David Wesner

David Wesner

Joined
Jan 5, 2005
Messages
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I'm tossing around the idea of making a curved platen. Something in the range of a 7" R. A poor excuse for a 14" wheel I know, but will it work ? I seem to remember the topic being discussed .... a long time ago. According to my sketches I can accomplish it with a 2" x 2" x 8" L piece of O1 or A2. Make it harder than Kelsey's nuts ! :) Has anyone tried this and what were the results ? Is it a waste of time ? I thought by positioning the platen just right I could minimize the contact area of the belt. Or just relieve everything except the area that the blade would contact during grinding. What say ye ? Anxiously awaiting replies ;)
 
There are several makers who use this approach on home built grinders - I believe Alberta's Ed Storch among them. It seems to work fine for him. I would have a number of concerns. With a contact wheel, the wheel moves with the belt resulting in less friction and heat. Using one section of the radiused insert would lead to wear that could not be mitigated with a ceramic type platen. Even a very hard platen will wear fairly quickly. Angles would have to be such that the belt actually contacts your whole working area, and not just single points of contact.

It works for some, but I've learned to listen to the voices in my head. ;) They told me to stick with a contact wheel. :D

Rob!
 
Rob! said:
It works for some, but I've learned to listen to the voices in my head. ;) They told me to stick with a contact wheel. :D
Rob!
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I'm hearing the same voices ;) I just had to ask though. I revisited the idea in my head late last night in the shop. I want a bigger wheel too.

I got a quote for a 2" x 14" plain face contact wheel from CRC about a week ago. 60 Durometer (may be a bit soft ??) with bearing, $ 383 with a 3 week delivery time. Not too bad a price at all. In fact when I consider the material, machining time, R & D , and the fact that it may not even work well, the curved platen would end up costing twice as much as the contact wheel. Thanks for the insight though :thumbup: :)
 
David, FWIW, the curved platens I have heard of mention radii of 2.5-3.5 feet to mimic the old British and European "lay-down" wheels. Even those create a large bit of drag and need a very powerful motor.
 
I believe Alex Daniel's uses one, but I'm not sure of the size. Probably something along the lines that Mike mentioned, because if you look at the blade from the point to the guard you can just make out the radius.
 
I think you might have some problem with the bounce you would get where the belt is joined together. Some of the grinding I have done on a flat steel platen with no padding gives undesirable gouges in the metal. You might be able to minimize this with a smoothing running belt like Trizac. I tried padding my platen with nylon and it melted it in no time.
 
David you might want to look on Ebay under contact wheel. There are 2by 14 inch wheels 55 duro for opening bid of 100 has 1 1/2 center. Check it out. Under the WAYNE gODDARD BOOK HE ALSO SHOWS MAKING WOODEN PLATTEN TO DO BIG WHEEL HOLLOWS
 
I know a guy who grinds his initial grinds on a 14" wet wheel stone grinder and then uses a wooden curved platten to finish the blades. I will have to ask him how he constructs the platten and see if its any different from the Goddard one.
 
I looked at the wheels on ebay. The price is great but is the 55 duro stiff enough? Whats the deal on retreading these things if its to soft. I could probly scare up some bearings easy enough. Thanks
 
fitzo said:
David, FWIW, the curved platens I have heard of mention radii of 2.5-3.5 feet to mimic the old British and European "lay-down" wheels. Even those create a large bit of drag and need a very powerful motor.
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Gosh Darn it fitzo. It seems everytime you help me out with a question I end up researching other topics for the next 6 months :D ;) Now its " British Lay Down Wheels " :D WOW, a 5' - 7' dia. wheel ? I can see the factory in my head now....... belts and pulleys running just over the tops of your head driving machinery :) You know that may be a viable option (the very large radii platen), a 5'-7' wheel would almost be a flat grind on a 1-1/2" wide blade, yet still hollow, and might would work quite well. I'm going to make a large compass with string & pencil just to see what something like that would look like, Thank You :thumbup: :)

And thanks to everyone else for the hot tips, advice, etc., I really appreciate it guys. Thank you again :thumbup: ;)
 
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