Air cushioned platen prototype

Sounds like it would be a great experiement and I look forward to seeing it developed. I know what it is like to get an idea in your head. It will haunt and chew on you until you build it. The thrill is in the hunt, not the kill.

I am still waiting for the seemless non-exploding belt to be developed.
 
first thing i thought of was stager the holes that way there is less chance of ware lines ( if there are any )
i hope it works out
 
I like it. When I used to work in robotics and automation we used air bearings for different things and they were great. We also used something similar to what you have shown for "floating" flat panel glass down a conveyor for sixty feet while it was being examined. I say "Go For It"! One way to keep air going where you want it to is by making multiple plenums in the back and using needle valves to each plenum to balance the flow. You may find that the air holes need to be different diameters in different zones (we did) to accomplish the task.

Once again, great idea!

Stevo
 
Here's a shot out of my Square Wheel manual demonstrating an optional 'air cushioned deadhead' attachment:

Thought this might offer something like hope for this design!
 
I think it will work great. There may be some fine changes but the air table on my friends half ton milling machine works fantastic.

Good move Rob!
 
Alan Molstad said:
The truth is that it will be more like placeing your hand down flat on the air hocky table,,,Your hand feels no air hitting it from underneath,all the air just goes around it..
Click to expand...
True, but not!.....
If you don't use much air pressure, this will be true, but if you use more, then I think it will work.
 
MrPurple said:
Here's a shot out of my Square Wheel manual demonstrating an optional 'air cushioned deadhead' attachment:

Thought this might offer something like hope for this design!
Click to expand...

I'm not sure what that is...but it sure sounds cool!! It is like a small wheel attachment...except the small wheel is really not a wheel...but an air cusioned bar that the belt rides over...?

Hmmm.....an air cushioned small wheel attachment....

Great!! I'll never get any sleep now.

I definately want to know more about that "deadhead" thingy....can explain it more..?
 
well, from my experances with air systems i really dont think it will work out as well as planed for these reasons:

-you will not be able to make somethign that can vary the psi behind it as the lowest point will change, espicaly when running from the same main air source, remember air will take the path of least resistance.

-even if you had 1000 air sources set at the same psi you still have the same problem of air only pushing X amount when some parts need mroe or less

-the only ways i can see as cost effective to vary the air out put either a.-will still create drag, high spots, and wear on the belts, or b.-will not be cost efective and take custom built software/boards and lots of electronics.



now even though all that is said i woudl like to say it is a very cool idea and very creative, i assume it woudl do at least some of what you want but personaly i wont hold my breath.

keep up the work, hopefuly you will be able to figure out a way to make this work.
-matt
 
rfrink said:
I definately want to know more about that "deadhead" thingy....can explain it more..?
Click to expand...

Unfortunately, I can't, Rob... I can't even find mention of the piece on Wilton's site!

Nonetheless, the concept is inherently the same. I think the difference is in the overall amount of pressure required... as Bruce mentioned, there's already a bunch of things similar to this used in industry. the parallel used about an air hockey table is a poor one, as it relies on surface area and high volume low pressure. This will require high pressure, as the deadhead device describes.
 
IMHO, how well this works is secondary to the fact that Rob is constantly trying to make better and more useful products!

Thanks Rob!

John
 
Rob,
I think Alan has some points. It is not so much like an Air hockey Table as it is a Hovercraft. The air pressure has to be contained in a patterned area to provide the lift. I have built two small hover-crafts, and can tell you that it is amazing how much lift you get (Hundreds of tons on larger units) from only a small amount of fan pressure. It is the minute film of air that does it. I would reconfigure the ports to allow the holes to all fall under the belt with no holes for the outer 1/4" on the sides to act as the "curtain".This way the air will create a pressure ridge under the belt,lifting it and allowing it to ride on a cushion of air.
The side blast of air and the low pressure area it will create around the belt edge will be a problem for those who want their dust to go downward.You will have to add side vacuum ports on both sides of the platen to take care of this. That would not be too much of a problem if you have a good dust collection unit.It would have to be built into the air platten to make it easy to hook up and all.
Stacy


Rob, If you want some layout drawings and a little engineering on this,email me.

Added:
After making some drawings and calculations, I think Alan's summation that there will be spillage from the pressure area of the belt (where the blade contacts it) allowing the air to lift the belt in all the non-contact areas will be the case. You might try just having the holes in the area of the contact.(maybe a 1X2" area). That would only add lift in the area of inward pressure, With the bleed providing cooling air under the rest of the belt. Maybe???
Stacy
 
Hi Rob,
Hard to tell by the pics, but if the dividers in your manifold touch the back of your platen, maybe you could tap for a few stategic bolts to run in and out as mini gate valves. Might help fine tune the air distribution (if needed). Thanks for sharing the fun project with all.
Take Care, Craig
 
bladsmth said:
I think Alan's summation that there will be spillage from the pressure area of the belt (where the blade contacts it) allowing the air to lift the belt in all the non-contact areas will be the case.
Click to expand...

This is just my guess,
But my guess is that the air will lift the belt a hair high, then a gap will open up someplece where you are not pressing the knife into the belt, and all the air will rush to the gap and the belt will flap like a flag ,
This will just go on and on like that all the time..

Anyway, what are you attempting to do anyway?...
Are you after 'lift"?
Or are you after cooling?

I was just thinking that if you were after the "cooling effect" of air under the belt cooling the platten, then the best way to go would be to cut small paper-thin groves on the surface of the platten to connect all the drilled holes with the sides of the platten.

This would allow all the rushing air under the belt an uninterrupted path out from under the belt, carrying with it the heat from under the belt.

I think you want to keep all the air flow going as fast as you can..
Any trapped air under the belt might be good for lifting the belt, but my concern is that it is not cooling anything.
Would not any Trapped air still be warming air?...

allowing a path so that some air is always slipping out from under the belt at all times no matter where you are pushing steel into the belt might be better for cooling the plattten
 
If cooling were the issue, what about just a large rolling platen? A wheel about a foot or two in diameter would have an arc very close to a straight line and would have rolling contact with the belt, so there would be no friction between the two. I assume that getting as close to a straight line would be optimal for grinding?
 
I need a totally flat platen....
Thats the only way I could make my blade sides flat...
whatever design you come up with, the thing cant have any curve at all to it...
 
Rob,



I think you only want air to blow thru where you are making contact with the platen.
If you are not grinding then there is no need for the air to pass thru.
If you use a small spring loaded (or air loaded) steel (or other) ball bearing to seal the hole until you press against it then only your contact location gets the air pressure. When not having pressure applied the belt would run on ball bearings.
This is the principle used on an air table we have at work and it works like a charm.
We are using it horizontal, I'm sure the challenges will be differant when it is vertical.
If you have a large cabinet shop near you go look at the air table on their beam saw to see exactly what i mean.
you will need to produce a tiny ball check valve that will work for you.

Kelly
two cents please ;)
 
The first try-out is complete! I'm excited with the results! Mostly as you would expect though. If you keep the work piece flat and square on the platen then you can feel everything float on air...it is nice! If the blade is slightly tipped or unsquare, then the air releases to the opening and the belt will rub the platen plate with the usual "thump, thump, thump!". Also, if you press hard enough, you can ground the belt into the platen by over powering the air bed.

For the first tryout, I taped off all of the holes in the platen except a 2" wide patch where I was grinding. Having all of the holes open, consumed too much air. I think the holes need to be much smaller as well. They are 1/16" right now...but maybe 1/32" or even 1/64" would do better.


I think the next step is to get this in the hands of a few knifemakers. The ideal candidate for a try-out would be someone who mostly flat grinds. ..bowies and big camp knives. Anyone interetested? You need be be somewhat seasoned and have a KMG.

Perhaps several guys could test it. Try it for a week then pass it on to someone else. Then the last guy sends it back to me. The guys that do the testing need to be open minded...unbiased, and required to report an honest evaluation. You are not going to hurt my feelings if you think it sucks (hee hee).
 
I have a good size order of each one of these models going to Italy. I have the steel on my bench as we speak ( A2 ) and am just getting ready to do layout and sawing.They are 13-1/8" OAL & 14" OAL , broad, good size Blades, Flat Ground. I'm not sure when you would be ready with proto-types of the platen but I have been making a good many of these as of late, so if you're not ready with one for this batch I have more coming up.I guess what I'm saying is if you so choose, I would be more than happy to test & report my findings on one of the proto platens.I'm sure you'll have no shortage of applicants.;) There are a good many here much more qualified than I am but I will still offer my assistance.
 
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