Big contact wheel........really big one

[Natlek]

I want to make contact wheel about 40 inch dia. Aluminium is out of question because of cost and probably availability .I have micarta in right dimension but it is heavy .Wood is only logical choice to me , but which wood is best to use ? Rpm would be around 300-350 so I think that will be safe ? Any idea ? Or other material to use ?
I already have axle and bearing ...30mm shaft and two double row bearing is enough I hope ?

 

[Stacy E. Apelt - Bladesmith]

I would suggest marine grade plywood.

 

[mike-E]

I would use whatever airplane propeller makers use to build props. Good luck.

 

[Stacy E. Apelt - Bladesmith]

Propellers are made from a high grade plywood, called aircraft grade plywood. It is better than marine grade plywood, but has thinner laminates and less knots. It is also a lot more expensive.

I have made boats and kayaks from Okoume marine plywood. It is an African wood. The layers are very thin and strength is high. I make small projects from aircraft grade plywood I get at RC hobby stores.

Many years ago I helped a friend of my father make a rope lift for a family ski hill on his farm. He used a jeep rear axel and gear box transmission powered by a two cylinder diesel motor. All the materials were Govt. Surplus (and I'm sure the Govt. didn't know some of it was surplus). The drive wheel was a huge pulley we made from plywood. We laminated two 48X48" sheets of 3/4" marine grade plywood together with fiberglass epoxy and drilled holes in the center to mount it on the brake drum with long bolts. We "turned it to shape by first marking a 40" circle by rotating the square, then sawing it roughly round with a hand held saber-saw. He sanded it smooth and round with a hand held belt sander while the wheel was spinning. We then laminated a 48X48" piece on each side of that and did the same thing to make the 48" outer parts of the pulley. When done we had a 40" pulley sheave with a 4" high sides. When done, the whole thing was given a couple coats of marine epoxy paint. The motor and powered wheel, as well as a big cable reel for the rope to be stored on were mounted on a trailer. I thought it was really cool how he made a clutch by using the parking brake on each end of the axle to start and stop the big pulley. Apply the brake to the unused wheel and the pulley rotated, release the unused wheel brake apply the brake to the pulley end and the unused wheel rotated. A 1000 foot roll of 1" sisal rope was spliced into a giant loop and was run through an ancient wooden block pulley that would be attached to a tree at the top of the hill. You grabbed onto the rope and skied up the hill.
I never got to go to their farm and ski, but heard that the kids and grandkids loved it and skied until they were too tired to stand up anymore.

One thing I remember is that he laminated each sheet of wood at 45 to the next one for more strength.

 

[Natlek]

Plywood ......I like that idea ,they are straight and can be glued together easy to get thickness I need . I will search what I can find here. I know of waterproof plywood which is used here for concrete pouring ?
I m thinking of making 3 inch wide wheel ,what do you think about that ? Four inch is maybe better but will be more complicate to make , maybe too heavy and cost of belts will jump to sky

 

[John mc c]

That waterproof plywood used for concrete is the marine ply Stacy is talking about.its called marine ply here too when you're looking

 

[Natlek]

That waterproof plywood used for concrete is the marine ply Stacy is talking about.its called marine ply here too when you're looking

Thanks for explanation my friend I can get of that plywood here . . . Well I must start from somewhere ... I have shaft and I just ordered SKF timing belt/power transmission PHG 3150-14M .That in number is ..... 3150mm length , 10mm thick and 75mm wide belt .
3150mm is little more then one meter dia./3104mm/ wheel but we will adjust that on lathe.And I think that my friend would not be happy when he see me with that plywood in his machine shop ....but It is not my fault that only he has so big lathe If someone some day kill me it will be him
PS . about this kind of belt , you can order width of belt you want ...

 

[WC53]

Have made small water wheels using marine or mdo plywood. Use a router cirle jig for the circum and patterns for spokes. Use the first as a template for router. Vacuum laminate and glass to seal edges. We used a belt sander held in a jig to true them as they were slowly turned.

 

[Natlek]

Have made small water wheels using marine or mdo plywood. Use a router cirle jig for the circum and patterns for spokes. Use the first as a template for router. Vacuum laminate and glass to seal edges. We used a belt sander held in a jig to true them as they were slowly turned.

I plan to use 3 x 25mm thick piece of plywood .Gluing will do in composite factory /for micarta,G10 and stuff like that / close to me .I have friend there ,they have all equipment for that .
But you give me idea.. . Maybe I will stay alive Other friend make big CNC router for furniture industry , one of them was sell locally and I know the owners . They will cut that three piece easy and very precisely .On lathe just to true up after all was done and on right size to press belt on

 

[Stacy E. Apelt - Bladesmith]

Take a look at this build. It is what you want to make. See how some of the problems are addressed. Also, see how much of a shaft and bearings it takes.
https://www.bladesmithsforum.com/index.php?/topic/15046-old-world-grinding-meets-the-modern-west/

It looks like your axle is from the front end of a car. You will have to make/get much longer bolts. I would be concerned that the two bearings will be too close together for the size of the wheel. Whatever they mount on has to be rock solid and heavy … with a wide base footprint that goes under the wheel ( or it will topple over).

I plan on making the 40" to 48" wheel for my kaiten toshi from plywood, but the shaft will go through the wheel and have bearings on both sides. The drive side will have two pillow block bearings with the pulley between them, and the other side will have one bearing that can be slid off the shaft fort belt changes. I will cover the edge of the wheel where the belt runs with hard rubber. I have been thinking about the width like you have. I will probably go with 4" because … what is the point of making a big wet wheel that isn't wide, too.

As to speed, using a 48" wheel as an example:
100RPM is 680 surface feet per minute. That works to a tad more than eleven feet per second. 350RPM would be 2390sfpm.
I can't see a need for a large wheel to turn that fast. That is a fair speed for a belt grinder. I was planning on running mine between 50 and 100 RPM.

 

[Natlek]

That part is from bike for rear wheel ..... It is very solid I think.If it can handle weight of bike and two man on bike I think it is enough for this project ? Plan is this .... contact wheel will turn on that two bearing ,part from side of that three large bolt fixed to chassis ? Distance between that two bearing is 4 inch ..
About grinding belt speed ...I don t want to go under 20m/s .. 4200 SFPM .
I found some data for okoume marine plywood ........Density: 500 kg/cbm
I will calculate how much will weight wheel but I don t think it will be too heavy . . .

 

[Natlek]

Ok, few days ago I visited my friend in his furniture factory to talk about cutting wheels ......and guess what they are doing in one of CNC router when when I entered inside .................. wheels , they are cutting big wheels from MDF
When I see how look big wheel , 40 inch wheel scares me . I recently ran into one thread here .....I can not find it again The story was around semicircle on different Dia. wheels and how much is close to flat it is ...forget I can t explain in English , sorry .
I make drawing to explain ...How big wheel we need to say that on 2 inch blade that wheel grind almost FLAT ? I wrote almost flat i know that it is still somehow hollow grind , but .......... My point is ....how big wheel to make so I can grind 2 inch wide blade almost flat ? I just need to know that so if smaller wheel do job no need to go to 40 inch dia? Can someone calculate that ??
Another thing , I think that I will go with 2 inch belt on this contact wheel not three inch .I will grind free hand and I don t think that I can apply enough pressure on three inch belt to grind right way.....
Thanks for any help

I ask about this .....how big wheel we need to say that two inch part of wheel is almost flat ...almost

 

[Sam Dean]

Does this help?

The rectangle is 2'' X 1/4'', and the arcs show the amount different diameter wheels would remove if ground to center. Even a 40 inch diameter wheel has a pretty pronounced "hollow" (exactly 0.0251'').

 

[Natlek]

Thank you very much Sam Dean ,thank you That was exactly what I was looking for ............
I rotate drawing so I can better see ......I think that something like 30-35 inch would work ......two inch wide grind on blade is rare thing I will do , even on kitchen knife ....I wrote that dimension just for reference to see how will look grind

 

[Sam Dean]

Thank you very much Sam Dean ,thank you That was exactly what I was looking for ............
I rotate drawing so I can better see ......I think that something like 30-35 inch would work ......two inch wide grind on blade is rare thing I will do , even on kitchen knife ....I wrote that dimension just for reference to see how will look grind

No problem! I've been doing this when I'm designing a blade & trying to figure out the height of the grind as it relates to stock thickness & contact wheel diameter.

 

[Atlas Knife Company]

So, what you really want is a 48" or 60" round platen? Usually about 4-6" tall with the radius machined into it to simulate really large grinding wheels. I think Nathan the Machinist has made some in the past. I just ordered parts to make a run of 25 that will be 30" radius equivalent. Not really very expensive, and makes a neat hollow grind.

 

[Stacy E. Apelt - Bladesmith]

It was Nathan the Machinist who makes the very good radiused platens.

 

[Natlek]

So, what you really want is a 48" or 60" round platen? Usually about 4-6" tall with the radius machined into it to simulate really large grinding wheels. I think Nick Wheeler has made some in the past. I just ordered parts to make a run of 25 that will be 30" radius equivalent. Not really very expensive, and makes a neat hollow grind.

You can not grind bevel on that kind of platen fast as like on contact wheel backed with rubber , especially not at high speeds . The difference is too big and not just that , on contact wheel temperature is very , very much lower , belt will last much more , profiling blade is incredibly fast . . . . No , personally I would never come back to flat platen ......never .After grinding dozen blade on my new 17 inch contact wheel , no way ! I will make if it is necessary 50 inch wheel
So far I have 3 inch ,8 inch contact wheel , almost done with this one on picture which is 10 inch/waiting for timing belt/ , have 17 inch and with this huge one i think that I will have all I need ...I think

 

[Atlas Knife Company]

Thanks Stacy, yes, it was Nathan the Machinist that made them. To be fair, both names do start with an "N" and the "M" is just an upside-down "W", so I was close

 

[Natlek]

Well , finally I have big wheel .... I found it where I did not expect I have two big compressors in my service .One run all time and other is spare when i need to do same repair on first one .Well , after about twenty years of work and repairs it has fallen apart and it is no longer worth investing money in it
Now hard part......to ask how much money they will ask to put some polyurethane on this thing .....I hope I don’t have to sell a kidney
I will make it 3 inch wide , I think ? Two wheel grinder /2,4 meters belt / and about 23 m/s belt speed is plan.Big wheel will have about 600 rpm to get that ...........it spin faster on compressor so i think it is safe .
Lathe first now , my friend would not be happy when he see me with this