DIY belt sander

[RichardM]

Here's mine, 3/4HP motor 1428 rpm direct drive onto the rubberised drive wheel (old heavy duty castor wheel),


top roller is crowned for tracking adjustment, black knob adjusts top roller mount.



Double springs (motorbike valve springs) are for belt tension.



I would say make it to suit belts which are readily available, but looks like you have sorted that.

 

[Robert1998]

Here's mine, 3/4HP motor 1428 rpm direct drive onto the rubberised drive wheel (old heavy duty castor wheel),
View attachment 332777

top roller is crowned for tracking adjustment, black knob adjusts top roller mount.

View attachment 332779

Double springs (motorbike valve springs) are for belt tension.

View attachment 332781

I would say make it to suit belts which are readily available, but looks like you have sorted that.

Thank you. This is just what I want. So, the crowned wheel must be adjustable, isn´t it?

 

[h-dom]

Another tip, I don't know what size belts you are using but don't bother with AO or even the cheap ceramic belts, I use the 3M cubitron and yes it's more expensive but I would say lasts five times as long, and cuts quicker and cooler. I only use AO when I get to fine grits.

 

[RichardM]

Thank you. This is just what I want. So, the crowned wheel must be adjustable, isn´t it?

Yes the crowned wheel (top) is adjustable, the block to the left of it in the second photo pivots at the top and the crowned wheel runs on axle off it.
The lower drive roller is not crowned.
Tension is provided by the aluminium plate pivoting at the back frame upright.

 

[Robert1998]

Thank to both of you for your help

 

[Robert1998]

Oook, I have bougth a new brand motor. 0,5Hp and 3.000rpm. I have made the support for the crowned wheel in 6mm mild steel and the motor has a 14mm diameter shaft whith a threaded hole for a m5 screw. the shaft is 23 mm long. I have also bought 2 rubberized wheels (Cast iron) 100mm outer diameter, 35mm the hole and 30mm width (The sandpaper band is 50mm)



And a 150mm disc for the angle grinder with velcro to the disc of sand paper. The hole is a M14 thread

.

I have to fix the wheels and the disk to the motor shaft.

Im thinking to make a cylinder 35mm diameter and 80mm long to put the wheels on it. On the left side it has a 14mm hole to the motor shaft, and in the right side it has a threaded hole M14 to put a M14 screw to fix the disc. And all along the center a 5mm hole to fix the cylinder to the shaft with a M5 screw.



This is all together. The cylinder with the weels on it, fixed to the motor shaft and whith the disk attached.




What do you think about this set up?

I´m thinking about make the cylinther of aluminium because is easy to machine and I´m not very skillful with the lathe. Make it slightly thicker than the wheel hole and keep it in the freezer to shirnk it.

And about the hole with the M14 thread, for the screew of the disk, I think I can´t make this internal thread, so maybe I make a hole and put inside a nut.

 

[h-dom]

Hi Robert, looks good except surely it is a male (external) thread you need m14 on the end for the disc to screw on?, so simply machine down to 14mm and use an M14 die to create the thread.

 

[Robert1998]

Oook, thanks for your answer. In that case I´ll do it of aluminium to cut the tread easier.

 

[Robert1998]

Ok, I´m going to make the cylinder of aluminium 6068 and the wheels are of cast iron and it has a hole of 36,6mm.

I can heat them maybe 40 or 50 ºC and I can put the cylinder of aluminium in the freezer -23 ºC so when everything reach the same temperature the wheels stay stuck in the cylinder. I have llok up in the internet about thermal expansion coefficient but I´m not rusre how to use it here.

So, What diameter should the cilinder be?

Thank you!

 

[brightspark]

if u dont want to be critical and fanny on just make them a slip fit and locktite. /they will never come off

 

[RichardM]

I usually work to 0.001" for every inch diameter.
Tolerance charts hera:

http://www.haydon-precision.co.uk/Tolerance%20fit%20charts.pdf

but if it is for the drive wheels I'd Loctite it as suggested by @brightspark.

 

[Robert1998]

Thanks for your answers.

Ook loctite. Regular loctite superglue is OK? You know regular Cyanoacrylate

​

 

[brightspark]

id use nutlock or regular loctite not superglue

 

[knighty]

the centre piece you're making to go between the wheels?

why not just add a step to the back (motor side) edge to stop the wheels going on too far

and then use a disk (like a bit washer) on the other side (m5 bolt holding it on) to stop the wheels coming off?


that'll keep it all lined up perfectly for you?


I have no experience with these, but decent bandsaw setup experience.... I wouldn't bother with the angle grinder disk thingies... by the time your belt is trying tor un off the wheels and rubbing something it's too late anyway..... also any kind of plastic will be rubbed through pretty quickly even by the back of the belt?

 

[Robert1998]

Thanks for your answers.

The angle grinder disk is only an experiment. The main thing is the belt. The plastic of the wheels is very hard, these wheels are made for heavy things

The wheels are tight in the cylinder. And I have used loctite. The glue is not for avoid them run out, but to transmit the force from the motor, but I think there was no need, because they fix very tight.



Now to finish I´m going to put the crowned wheel on the top.



I have a hard shaft from a industrial printer 14mm diameter. But is being hard to find bearings for that diameter. Instead, can I use 15mm mild steel for that purpose?

The shaft is attached with a pin in such a way that it can tilt moved with the screw, to change the inclination of the crowned wheel.

And to add tension, I´m going to put a 3rd roller with a spring

What do you think about this set up?

 

[Robert1998]

Hi one question. Maybe a silly one.

Is it safe to use gray cast iron as wheels? They are going to move a 2800 rpm.

 

[brightspark]

wont be a problem at that diameter

 

[Robert1998]

Thank you!