New rotary Platen for BurrKing and Hardcore..(pics)

rfrink

rfrink

Joined
Aug 1, 2000
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This is what I have in mind for the BurrKing and Hardcore attachments. The drive wheel is 4" diameter. The main side bracket clamps on the spindle with a split hole ..the same as the other attachments for these machines.

The center roller can be removed or added to provide some additional belt stiffness.
The upper roller is adjustable for tensioning using the same components as the Rotary platen design for the Bader/KMG1.

burrking.jpg


Since I'm still in the prototype design stage...What do you guys think? What would you change? what do you need that this doesn't have?...etc.

We have a blank sheet of paper to work with.

Sincerely,
Rob
 
Mr. Frink....your ingenuity never ceases to amaze me.
Please consider an attatchment to fit a "BEE" modle 50 belt grinder. It is very similar to a square wheel. I think you will find that a large number of us Canadians use this grinder as it is Made in Woodstock Ont., and with the difference in the U.S./Cdn. dollar a lot of small time makers like myself have to rely on "home-grown" equipment. If you like I will send you some photo's and specifications.

Jim Ziegler
 
The only thing that I can think of, at the moment, is to curve the attachment arm back, very shallow U, like the stock unit. The extra wheels, between the top and drive wheel, I would think two, could be on a plate that would bolt in like the platen on the stock unit. It could also be made adjustable, in and out, for tensioning.
I am not criticizing your designs by any means, this was just something that occured to me on the spur of the moment. ;)
Edited to add: I am referring to the 960 Burr-King here.:confused:
 
one litle idea, would there be a way to make a wing nut ajustment for the palten belt tightness? this would speed things up when changing grinding belt grits. that way you could loosen just a hair as you move to finishing belts.
 
I think the biggest thing I see "wrong" with this unit, is that it's in that picture and not in my shop! :)

Very cool Rob! What's the projected cost and how long is it looking before you'll have them in production?

Nick
 
Rob,
As you are aware, I have a VS Hardcore grinder. The flat platen assy I have has a 5 inch drive wheel. I feel that even with this wheel the maximum belt speed is just tolerable. I am afraid that with a 4 inch drive wheel the belt speed would be unacceptably slow.

One other thing that I am mindful of is belt tension. With the small wheel on top, I have to really watch it. If its too tight then that wheel gets pretty hot. I have had to back the tension down some for a happy medium between tracking and belt tension. I really don't know what the answer is here, even if its much of a problem. I just thought that I would mention it.

Where would be the optimal place to grind on the belt in the configuration shown? Have you given any thought to an "optional" platen wheel in addition to the one shown in the drawing?

I hope the observations I have stated are not appearing as being critical, that is not the intent. It is just food for thought. Believe me, I know that when you are trying to design something of this nature that you really can't please everyone. That's impossible.

If you would like to discuss this further, shoot me an email if you like. Maybe we could talk over the phone. The rotary platen attachment is looking good.

C Wilkins
 
This is great! I appreciate the thoughts...and it has made me aware of a few issues. Heck don't worry about criticism....lay it out there....whatever comes to mind. It is much easier to change now then later.

CL, I wasn't aware of the speed issue, and after looking at the Burrking Knifemakers attachment, it also comes with a 5" contact/drive wheel. I didn't think about it earlier.....but heck, why not just use the original 5" wheel.

Mike, great point about the center wheel adjustability. I played with the idea very earlier and talked myself out of it. The reason is that the tension is easily adjusted with the top roller...so no need to move the middle roller for tension. The reason for the center roller is to shorten the span of unsupported belt,... to provide a flatter grind. I placed it close to the drive roller thinking that most your work will be grinding somewhere on the belt face in between these two wheels. Then if you need more slack/convex shaping, you can move up a bit and work in between the top roller and the center roller...then for the most convex/slack, simply remove the center roller.
...hmmm, now you have me second guessing myself.....maybe I just need to build one of each and see.

In the design above, it may be hard to pick up on, but the center roller is slighty out in front of the other two rollers. This pulls the belt out about .100" from where it would normally run.

Laurence, Great point about the tensioning! This has the same system that the KMG1 and BaderIII attachment uses. The details are not drawn in this CAD model but it is very quick. There is a tensioning screw on the top roller that when tightened will pull the roller up to tighten the belt...it works very nicely with a "t" handle allen wrench.

Nick,
I haven't thought much about the price at this point....the first thing for me is to make sure it is a good product. I have a few makers lined up to put the prototypes to the test. I'd say that after they run them for a month or so and we tweek the design as needed...then everything else will fall into place. Your just like a kid! :D " can I have it now, can I have it now, can I ha....":D
Thank you for the note!


Jim,
Thank you for the kind words! I have plans for a square wheel design. Hopefulley it will fit your BEE. But I can't get to it for a few more months though.


Keep the comments coming. Don't worry about criticism...or bruising my ego or telling that I have an ugly baby.:( ....(hee hee). Your "off the cuff" comments and ideas are very valuable!

Thanks,
Rob
 
Rob,

This looks great, as usual. It's really nice to see you expanding your product line.

My question in this: On the left side, how much clearance is there between the "frame" of the platen and the platen itself? With my big hands, I am a little cramped on the left side of the Caffrey platen, where the tooling arm, platen frame, and platen itself are all pretty close together. Having the platen frame protrude an inch or two beyond the tooling arm would solve similar problems.

John
 
Rob I have an almost exact copy of that rotary flat grinder eccept not as pretty and I found that I can use an eight inch drive wheel and never really have to convert my machine arround to do both flat and/or hollow grinding.I just use a grooved aluminum 2" wheel and the serpentine belt over the standard contact wheel,the small wheel keeps the serpentine belt tracked properly and I can still adjust the tracking on my sanding belt. So its not necessary to make an extra drive wheel.It also changes my 8"wheel into a 8 5/16 wheel.Just make sure the tracking adjustment knob for the 2"grooved wheel is easily accessable . Great job Rob !!! I want one of these as soon as I can get one as I'm sure yours is much steadier than mine.So please put me on your list.
 
Sorry I forgot to add some small points.
The other reasons I like to use my 8" drive wheel is cause it shortens the distance between the two wheels , I can grind flat or hollow without any conversions,it also gives me more room on the left side of my burr king so I can grab a fist full of knife and not bang my nuckles into the housing ,and because I couldn't find a short enough belt to use the five inch wheel (which turned out to be a blessing in disguise ) BTW I love the third wheel option to stiffen and shorten as youl find it takes a conciderable ammount of tension to grind a truely flat blade. Your third wheel will no doubt lessen the grief on the bearings.
I am eager to try one !
 
Rob,
Ken Onion may be on to something there...

One of the BIGGEST complaints I "had" about the Hardcore is changing from a flat to hollow grinding setup. I very rarely, if ever, hollow grind any more. But I am sure there are those that do.

~but~

One "opportunity" however is that it will be difficult, if not impossible, to run a 72 inch belt, unless the idler wheel is changed out to a smaller size. For my 10 inch contact wheel I have to run a 6 inch idler. With the flat platen assy, I run an 8 inch idler wheel. The 8 inch idler is used when an 8 inch contact is used. Math and geometry were never my strong suit so someone a little smarter than me will have to figure it out! :) This would definitely make the overall package considerably more expensive.

~and~

One other way to look at it is that this is for flat grinding and would be no more difficult to change out than the standard flat platen assy (if the 5 inch drive wheel is used).

~however~

The rotary platen assy could be left on the machine and "swung" out of harms way, remove the rotary platen belt, change to to a larger idler (with one set screw) and you are set up to hollow grind with an 8 inch wheel. Not much of a problem there...

Lots and lots of variables...

Oh heck!!! I think I'll just go get another grinder!!! :confused:
There's just too many moving parts...

C Wilkins
 
I would be concerned that a 5" wheel will not give
enough belt speed. I have a 8"&10" contact wheel
and feel that a 8" lower wheel will work better if
possible. Gib
 
I don't see the problem with belt speed. When I flat grind on the Burr King I have to use the knifemaker set-up and that's driven by a 5" wheel. I've always had plenty of belt speed with that arrangement.

I totally agree with John and Ken's sentiments on the depth from the grinding surface to the support arm (left side of belt). I really like Ken's idea of using the 8" wheel as that would greatly increase that depth and keep my hand away from the support arm.

I sometimes hollow grind clips with the 5" wheel, and it's really hard to hang onto the blade when grinding on the left side.

I also like the idea of being able to flat grind and hollow grind with one set-up. That is by far the biggest downfall to the BurrKing is the time it takes to change set-ups (IMHO).

But then again, I really like Craig's idea....now who can I find to sponsor the "Nick Wheeler Needs Three More Grinders" fund??? ;)

ALL very cool and very innovative. It's really cool to see how much "out of the box" thought is going into these.

Nick
 
rob, how about making one that has two wheels and will bolt in the two exsiting holes for the flat palten on the hardcore using the 2"x5" wheels? then a more improved version with a new arm and more clearance for us guys with ape size hands?
 
Rob, put me on your waiting list too. I like the 8" wheel idea if it can run 72" belts, but I don't mind the 5" either; belt speed has only been a problem for me at the high end.:confused:
 
Originally posted by Don Cowles
Rob, put me on your waiting list too. I like the 8" wheel idea if it can run 72" belts, but I don't mind the 5" either; belt speed has only been a problem for me at the high end.:confused:
Click to expand...

Don and I are apparently on the same page as far as the maximum belt speed goes. It is only on the high end. Once I go to a 220 grit belt it is no longer an issue.

There really is nothing wrong with the 5" inch drive wheel, the speed is "tolerable". My initial point was that I felt a 4 inch wheel would be too slow.

One other thing to consider is "if" an 8 inch drive wheel is used (thus a higher speed) then bearing life may become an issue on the smaller wheels at the top of the fixture. A larger wheel may be be necessary if so.

C Wilkins
 
Thats why they make varriable speed motors .I like to use the 8" wheel cause it is easier to grind the left side of the blade as ones knuckles are not banging against the housing and also because I can grind both flat and hollow without altering the machine.
 
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