Belt grinder advices

Hi all!
My uncle gave me some old but good engines, among which one 1,5hp - 2800 rpm, I'm thinking about building a belt grinder. I found on local flea market some abrasive belts, from 6cm to 12cm (2,3" - 4.7") various grit, very long.

My idea is to replicate a belt grinder with 4 pulleys, like kms (is that the name?) or like many good project seen on this forum.
I got a few doubts concerning diameters and width of the wheels:

- I havn't understood the use of large or small diameter in the final "cutting" wheel. I see very big, or couple of wheels (usually one bigger than the other) with a flat support, or smaller single one.

- If you need to build a belt grinder, which width of belt you should take? It may be worth building large width wheel (12cm)? Or It can be better make wheel for 6cm?

-Adjustable wheel for centering I see has "tip", I can immagine something between 5 and 10 degree, It can be useful?

- engine pulley diameter, as I understand it, it's only related to speed of the belt. For steel speed should be around 25-35 m/s and something less for wood. If I attach the first wheel at the shaft of engine, with 2800 rpm I should use some 150mm (6") or more in order to obtain cutting speed of something more than 20m/s.
...or maybe I should use a couple of pulleys to decouple engine and change speed? I think it's the right choice.

I'm searching for 6003 bearing, hope it's a good choice. I want also to add a cotton polishing arm :rolleyes:

What do you think about?

Shipping list updated
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Hi all!
I'm starting the project of belt grinder
I got long belts (3m - 120"), then size is not so compact, due to this point I chose to make a floor standing machine.
I was inspired by a youtube video of a diy grinder, very well made in my opinion.
I think I will make some attachments for cleaning - polishing.
Central tensioner needs a spring, don't know how much load belt needs, I will try maybe with attempts.
I'm also thinking to make a support with protractor, I have to think a good way to engrave steel
Some good idea to make the machine better?

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https://www.youtube.com/watch?v=9Ocb...2oO1-qxLJ6rsmx

I'm thinking about use some high density polipropilene as bel support on the double wheel final part, or maybe it's better steel?
Next work will be build the wheels on lathe, don't know if making them straight, or with double angle, it can help?

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It used to be that it was a given that you would always put a crown on the pulleys on a belt grinder but the one I have has no crown on either the drive or takeup pulley's. What I notice with this is the belt is more uniform in its usefulness. It doesn't have the slack edges that a belt on a crowned pulley would have. Mine also is tracked with what I think is ingenious method of twisting the take up wheel to track with. Personally I don't use long belts and use the disk sander more than belt sander and don't leave the belt on mine all the time so what do I know ? :)

[QUOTE=rendoman;67793]I'm thinking about use some high density polipropilene as bel support on the double wheel final part, or maybe it's better steel?

I'd tend toward poly/ urethane/ or non-metallic wheels to reduce inertia and heat retention. Aluminum tube with a plastic liner for bearings might work too.

Next work will be build the wheels on lathe, don't know if making them straight, or with double angle, it can help?
The tracking adjustment wheel might look flat, ok for regular speeds. Most have a very large radius, not a pair of angles, that's what stresses the belt. Crowned sheaves are used on things like toolpost grinders; high rpm, rubber with cords and 'no' stretch, perfect alignment and the crown keeps belt centered.

1,5hp - 2800 rpm is a lot of power and speed. A speed control might help if the calculations are too high drive ratio, and to handle different materials nicely. The belts you have will last a long time, spreading wear over more area than my 42'' (1066mm).
4 wheel sanders are called 'square wheel'. Typically there is a removable plate for smooth free-hand contour sanding. The plate makes it more like a grinder, to achieve flats, radius corners or chamfer edges.

... large or small diameter in the final "cutting" wheel. Larger wheels and 3 or 4 reduce belt stress, compared to bending around small wheels. Mine is 3500rpm and about 4'' drive wheel, upper about 2''. Mainly I think that is to gain distance between wheels. 42'' is not a common hardware store size. I ebay them.

Width to me = wider is better. Cutting them narrow could break the band of fabric or stretch unevenly. Design the plate to move side ways a little so you can sand right into a corner

-Adjustable wheel for centering I see has "tip", between 5 and 10 degree, It can be useful? That's the adjustment an eases the belt on without any tension. Mine sounds just like what C-Bag describes.


- engine pulley diameter, ... same as motorcycle gearing for different engines. Mine's 3500 rpm sometimes faster than I want. It sands wood fast enough to burn with a fine grit. Grinds metal well, iron or aluminum. Haven't found a belt good for thermoplastic, [those that melt], has to be brand new sharp. I think you could reference commercially made sanders for rpm they run in, but to actually to vary speed is way better. We'd probably use a step pulley.
Being able to change speed will allow a range for polishing too.

I totally concur Dr. TM51, especially about speed and hp. I know it's counter what most folks on here want but as one who's gotten tangled with grinders I don't want or need more rpm's and ESPECIALLY more hp.

My dad gave me a big old 1.5hp 8" bench grinder and I dubbed it widowmaker as it about sucked me into it way more times than I want to admit. And I'm one of the more paranoid users of tools I know. Even though I was terrified every time I used widowmaker if I ever got distracted it would bite me....hard! The best thing ever was when it decided it bit me enough and burned up one day. I don't ever remember being happy when a pivotal piece of equipement died but I did a little jig when I dumped that thing in the recycler bin. I felt like I'd outlasted an opponent not mourned the lose of a valued ally as I view all my tools. It got replaced by a Jet 1/2hp 6" grinder that I keep a wire wheel and the other side has a Multitool w/36"x4" belt 7" sanding disk on the other side.

It's as handy as a shirt pocket and has more than enough power for me. More is not better for me. I'd rather something bog down and stop instead of pulling me in to end losing a finger or worse. Just my 2c.

Thank you very much, both of you are a mine of information!
Maybe I made wrong calculations, 2800rpm engine, with 2,5" final pulley I calculated final speed of 8500rpm to reach speed in range of 20\35 ms of the belt. I have to search the paper for better accuracy.

I come back in few hours, time to go out see the match Ita - Ger :rolleyes:

Grinders, grinders, and more grinders.
I guess that I've never found one with too much power.
the old blacksmith shop where I apprenticed had 3 old arbor grinders 1 had a little 3 Hp motor on it with 2" wide 14" inch diameter fine grit finishing wheels on it that was the one we used to sharpen small cultivator shears.
One had a 10 Hp motor not real high speed but 4" by 20" coarse wheels would remove metal by the pound
The last one had a 45 Hp 4 cylinder Wisconsin it had 2 belt driven arbors on it 1 was horizontal with a single 10 inch wide 20 inch diameter wire wheel the other arbor was vertical with a single 20 inch diameter cupped wheel. this was used for grinding shear blades
One of my tasks was to keep all of the wheels dressed and true. In today's society I would no more trust a 12 or 13 year old young man with a diamond wheel dresser on a 1/2 hp 6" grinder let alone have him anywhere near those monsters. but I used them almost daily.
I like the OP's idea for a 1 1/5 Hp 2800 RPM motor fora belt sander/ grinder I would probably go with a 3.5 or 4" diameter 8 grove serpentine pulley to a 1.5" or possibly 2" driven arbor to power the flat drive sanding belt pulley make it changeable from about 4" in diameter to 6" in diameter
1 1/5 Hp will be a little on the small side in my opinion for a belt wider than 4 inches though and nowhere near enough for a disc much larger than 8"
My Delta 12" disc & 6 by 48" belt sander had a 3 HP 2800 RPM motor with a 3.5" pulley and the arbor had a 2" pulley it did a fine job but could be bogged down

hi all
Small update
I started welding frame, maybe I need some 45° reiforcements, structure is also stable.
Next thing to do. alu wheels and shafts

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Hi!
Slowy but I am continuing the work on grinder.
Next thing to do: front rest, last rear wheel + pulley and a stand for engine. I Have to finish the alu wheel, they are just mounted for taking pic
occult simbols are reminiscent of the cult of Priapus :lol:

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I'm thinking about adding a protractor to the support, just to set the right angle with no external tools.

Next thing to do is the ensemble large engine wheel + pulley and motor brackets, maybe the worst part to do... I got no flanged bearings, only normal type, I have to build a nice frame

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Rendoman;
It's going to be killer. If the worry about flanged bearings I bet you can duplicate what they do. If its end play [thrust] a spring and bearing ball [ball only] with a set screw could control it. Flanged, could be housed, or maybe auto front spindle bearings, [very common to rear wheel drive cars] drive taper is built in, use same on both sides, shaft shouldered one side, nut and cotter pin other end. They are inexpensive here. Lots of motorcycles use them too, even in swing arms. Hope the terms are universal enough that you can ID them. You might look at RockAuto for photo leads. Try 1965 Chevrolet Chevelle, they were drum brakes, RWD and occasional chick magnet.
My Italian language interpretation and translation can't get me past a dinner main course, and crummy desserts! Everybody else looks at the cart and KNOWS what to get!

Thanks for advice!
It's Always a pleasure to see american big engines and cars on parts site!
I built a kind of protractor from steel, I thinked different ways to solve the problem, but at the end I think that's the easiest. Wire in picture is only demo, I will make something more valid.
It's time to take measures for last wheel shaft, and decide motor alignment.
In last picture there is the longest belt 3m ( 118" ), I got also some shorter 1,8m, I think the outreach of arms is good, I hope to not have problems with vibrations, for this reason I put 12x m10 lock on both vertical and horizontal sheath.
Ps: this anvil is really beautiful! Hammering punches has never felt so good, Pieces motionless and sound attenuated, I'm happy:D


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...thinking the next step...
a good work maybe needs a couple of keyways, I can easily do with mill on the rod, but i got troubles doing them on internal of pulleys... Should I try with lathe and a parting tool? or maybe with 4\5 blades stick togheter? or maybe with a couple of grains ( I think the worst job possibile :rolleyes: )
In august shops are closed, it's difficult to find things, but here I not lack of imagination :D

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the way I make a lot of my internal key-ways is to run a small end-mill through the bore roughly removing most of the metal then chuck the part in my lathe and lock the spindle with the precut key way exactly on the horizontal center-line then grind a piece of HSS the size of the key mount it in the tool holder with half above and below center then I hand cut the finished key way using the carriage travel making very small cuts until I reach my desired depth of cut. you can do this without using the end mill first but requires more material to be removed by hand

Thanks FrankS!

I tried, not the best work ever done, but at least it works :D
I used 3mm hss for cutting 19mm bore. Now I'm thinking about the last wheel, bore is 15mm, the exact height of the tool, i got no insert or hss so tiny to be used.
I'm thinking of drilling the wheel+shaft and put 6 grains, or maybe i should use file till Tomorrow, trouble is that wheel is 85mm long, maybe a 30mm key can be enough :D

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I built this then made the video. Here's what I do. I guess I'll post it.
https://youtu.be/nZnp11EYAJ4

Very nice tool!!
Thank you and thank to Frederic that passed me a useful link to a similar tool

Question for you, it's ok about shape and operation, but what kind of insert can be used? I'm surfing aliexpress page for indexing tools and parts but there are really many type, they have a specific name?
Saluti
Stefano

Quote:

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Originally Posted by rendoman

Very nice tool!!
Thank you and thank to Frederic that passed me a useful link to a similar tool

Question for you, it's ok about shape and operation, but what kind of insert can be used? I'm surfing aliexpress page for indexing tools and parts but there are really many type, they have a specific name?
Saluti
Stefano

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You could build your own indexing head, look up Gingery lathe. He published a series of how to books on building your own machine shop from scratch. The series of books start with teaching you how to build a foundry, all the tools needed and furnace to melt aluminum. Then teaches you how to build a mold to cast aluminum to build a metal cutting lathe, milling machine, drill press and accessories. One book teaches how to build a dividing head or indexing head. I have built it and it works wonderfully. I still have and use the lathe I built from 35 years ago. Here is the link.
Gingery Book Store

I have to take a look, Good books are not easy to find!
Very rough work but functional, next thing to do engine brackets, maybe with a tensioner
I want also to add a plexi shield for eyes protection

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Looking good, I made a small benchtop version of this just to clean up shafts and edges of sheetmetal. Uses a 1" wide sanding belt, used a small double shaft A/C motor, just what I had laying around.

Hi!
I'm going to finish the grinder, I changed a little the project, due to add more simplicity on engine pulley. I can't do a good job with broaching, so I decided to make some holes with grains to link the pulley with engine.
I have to build a sort of frame for motor, and maybe add some reinforcement.

A couple of pictures as usual

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Accurate enough, even if it's not a perfect job.
I changed the position of motor, I don't know if convert the frame to fixed, since I will not use the upper shaft with pulley for speed.


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Engine wheel should be in right position, Tomorrow I will try to turn on and see what happens.


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Hi!
I changed the upper wheel because the one I built last year wasn't good. I increased the diameter. I should tune the front wheels-shafts and maybe try the first run.
I'm thinking about the polishing attachment

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Belt grinders are great machines in any shop. Seems to me that you are not going to get a high enough feet per minute speed on the belt because of the small diameter of the motor wheel even if the motor is 2 pole (3000 rpm). Are you getting at least 4000 feet per minute?

Hi!
With the combination of wheels (4" motor - 3" Others) and 2800 rpm, I should have 2932.2 ft / min according to calculator, it's about 15 m\s. According to 3M manual it's good for titanium, I should need 5 more m\s for perfect work. A 6" wheel can fix the problem, reaching about 22m\s - 4300 ft \ min, But i'm not happy to make a large wheel now, because I need large round aluminum bar, maybe in the future if the grinder will be not enough.


https://www.blocklayer.com/pulley-belteng.aspx

http://multimedia.3m.com/mws/media/3...g-industry.pdf

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It seems working!
I'm thinking about to put a spring in the vertical tensioner, but I don't know how much force is needed.
Wheels are planar, with no crown or angle, the regulation of belt path is so sensible.
Some advice in order to make a better machine?

https://www.youtube.com/watch?v=o07JtJCbifk&feature=youtu.be

Just finished the electrical system
I used a contactor with open and closed button, rated up to 4kw. I didn't think to put a safety mushroom, the buttons are close to working position.
I want to make the buffing- polishing shaft, and maybe a rear rest with the size of the belt, in order to use the edge

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You can supplant a e-stop mushroom with a hinged paddle. Make large as you care to. I like them, to elbow the stop switch when both hands are manipulating a wide part.

This one is turning out quite nicely. Regarding tensioning for belt sanders in general (not necessarily this one), I know people love repurposing treadmills for them - some of them have an incline motor (for simulating walking/running "uphill") that can be used for tensioning. In that case, you scavenge the treadmill's main motor for main power, the incline motor for tensioning, and the treadmill frame for your belt sander frame.

Thanks for the advice!
I'm modifying a part maybe intended for the same purpose, the original used a pulley for trapezoidal belt. I made with lathe only a wheel for the belt, kept in position with a grain, as the original place. Next thing to do a small frame, fast to detach for the long shaft already mounted on the sander.
The shaft is good for 15 and 20mm cotton wheel, or other attachments

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Hi Rendoman,
It is looking good. The more versatile you can make it the better. Having lots of speeds means you can grind many materials.I made mine so that it could take a wide range of belt lengths because I had access to them. I also built in the ability to have four different speeds via pulley counter shaft, plus other speeds dependent on which wheel was the driver (on motor or driven shaft), and the diameter of the contact wheel(s).Be careful to have suitable bearings on small diameter idler / driven wheels because they can rotate at high speeds if the driving wheel is of comparatively big diameter. Is your platten adjustable against the back of the belt? You might like to get the book called "Coated Abrasives- Modern Tool of Industry" written by the Coated Abrasives Manufacturers Institute which gives technical details about belts and machines, basically all M stuff.

Quote:

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Originally Posted by Frank S

Grinders, grinders, and more grinders.
I guess that I've never found one with too much power.
the old blacksmith shop where I apprenticed had 3 old arbor grinders 1 had a little 3 Hp motor on it with 2" wide 14" inch diameter fine grit finishing wheels on it that was the one we used to sharpen small cultivator shears.
One had a 10 Hp motor not real high speed but 4" by 20" coarse wheels would remove metal by the pound
The last one had a 45 Hp 4 cylinder Wisconsin it had 2 belt driven arbors on it 1 was horizontal with a single 10 inch wide 20 inch diameter wire wheel the other arbor was vertical with a single 20 inch diameter cupped wheel. this was used for grinding shear blades
One of my tasks was to keep all of the wheels dressed and true. In today's society I would no more trust a 12 or 13 year old young man with a diamond wheel dresser on a 1/2 hp 6" grinder let alone have him anywhere near those monsters. but I used them almost daily.
I like the OP's idea for a 1 1/5 Hp 2800 RPM motor fora belt sander/ grinder I would probably go with a 3.5 or 4" diameter 8 grove serpentine pulley to a 1.5" or possibly 2" driven arbor to power the flat drive sanding belt pulley make it changeable from about 4" in diameter to 6" in diameter
1 1/5 Hp will be a little on the small side in my opinion for a belt wider than 4 inches though and nowhere near enough for a disc much larger than 8"
My Delta 12" disc & 6 by 48" belt sander had a 3 HP 2800 RPM motor with a 3.5" pulley and the arbor had a 2" pulley it did a fine job but could be bogged down

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The amount of power you need varies with what you are doing. In the case of the original poster I'm not sure 1.5 HP will be enough. Those long wide belts can grind with an incredible hunger, so I would be concerned that 1.5 HP isn't enough to get the full monty so to speak out of the belt. Of course if you are doing fine finishing work on a knife or something you don't need that much power.

Small frame for polishing, recycled parts

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Quote:

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Originally Posted by wizard69

The amount of power you need varies with what you are doing. In the case of the original poster I'm not sure 1.5 HP will be enough. Those long wide belts can grind with an incredible hunger, so I would be concerned that 1.5 HP isn't enough to get the full monty so to speak out of the belt. Of course if you are doing fine finishing work on a knife or something you don't need that much power.

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Yep, interesting to note that the rule of thumb as per the handbook from 3M is "one horse per inch of belt width" which seems like over kill until you see the rate at which these belts eat metal when there is enough pressure on them...

Just finished the polishing attachment.
The belt run strainght with no trouble, the shaft for cotton wheel is 15mm with 20mm bushing, left threaded.

Now I have to buy wheels and pastes. Have you any advice?
I only have White paste, I think I need one wheel for each color of paste, right?
I want to polish aluminum and brass.
I think I need : light blue, pink and brown. There is also a green for stainless, but I don't know if it can be good as last passage before brown

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