Thread: Home built belt grinder/linisher design: belt backing plate.

I thought rather than hijack the thread on flame hardening 1045, I'd start another on building belt grinders and fitting a backing plate to the belt.

Originally Posted by gwilson

Sag: 1060 backing plane for a belt grinder is not going to last. Not enough carbon to have decent wear resistance. What I have used is A2. I drilled and countersunk a screw hole into each corner for flat head screws. I fully harden the A2 in AIR and leave it fully hard. I screw it over the cast iron platen. When it wears,I can turn it over.

D2 would be even better,more wear resistant,but the A2 has stood up pretty well.

I'm limited a bit in what's available locally, the counter jumpers at one of the bigger steel merchants have never heard of 4130 etc., and think I'm playing with them somehow. They have something they call "wear plate" so I'll have to see if they have a spec on it.

It's my first belt linisher/grinder unit, there are signs of black steel dust deposits in places on the backing plate after a few hours use. I ground the left over piece of backing plate that was hardened and cracked in the middle. I used a zirconium belt and was surprised at how easily it ground and how little it got hot for the rate of material removal.

The backing plate is a bit hard on the belt join and whatever you are grinding so I'm thinking of getting some of that thick graphite sheet to attach to it. The machine originally started out a 12" disc sander but had the belt parts added later and it will already be modified soon to put the spindle shaft on top of the brackets and cut off the top of the column tube to give the contact wheel more clearance when the belt is swung round to horizontal.

There is a bar fitted now behind the top idler to help guard against belt breakages and I have to alter the pulley ratios to slow it down as right now the surface speed of the belt is 109 KPH and the disc periphery is 160 KPH (100 MPH).


Basic layout showing the 8 inch rubber contact wheel at the bottom and the 12" steel disc. The parts
are actually 30 year old hand me downs from a friend cleaning his shop out.They are parts from two
different machines that just happed to fit together without modification. The Idler wheel is his own
casting and design, the long shafted knob is the locking knob and the knob to the rear right is the belt
tracking knob. Only the belt grinder arm and all the steelwork are of my construction.


Detail of the carbon steel adjustable backing plate arrangement.


Front grinding rest and bracket with adjustable angle and clearance.

Wow, your current belt speeds are Hooting along. Maybe i should go and measure the speed of my Linisher / radius master.

Originally Posted by GordoB

Wow, your current belt speeds are Hooting along. Maybe i should go and measure the speed of my Linisher / radius master.

I've used an early one of those and the motor does run at 1440 rpm with the same diameter contact wheel so it's running at half the speed of this one. I think they do claim their belts last twice as long too.

Originally Posted by SAG 180

The backing plate is a bit hard on the belt join and whatever you are grinding so I'm thinking of getting some of that thick graphite sheet to attach to it. .

I have a belt sander that has what looks like graphite sheeting that is worn out after 18 years that I need to replace. Do you have a brand or descriptive name for the sheeting along with a source?
Tom

Heller & sons has them for their belt grinders. Believe they come in 3" and 6" widths. Not sure about the lengths, maybe about 15" to 18".

Bob

I had a piece of planer knife stock probably M2 that I use on my Burr-king. If you bevel the edges on the plate the scarf joint runs smother over the back up.

Or, if practical have the back up off the belt in free run, it will wear the belt and the back up less. Once you apply a little pressure the belt will contact the back up.

Steve

Originally Posted by TDegenhart

I have a belt sander that has what looks like graphite sheeting that is worn out after 18 years that I need to replace. Do you have a brand or descriptive name for the sheeting along with a source?
Tom

I just know of it as graphite backing cloth, I think it's fairly common at abrasive shops.

Steve: I did radius the ends of the plate and it makes a difference, I've yet to run any scarf joint belts on it. The belt set up so it clicks a bit on the plate when I tap it with a finger.

GordoB,
How do you like the Radius Master, good / bad.
Sag 180 sorry for diverging the thread a bit. Thanks.

Nice beltgrinder but I hope your motor is dustproof.

Originally Posted by salzburg

Nice beltgrinder but I hope your motor is dustproof.

It is....I think all new motors sold round here have to be sealed units these days. The motor needs sheet metal dust cover as the motor fan does suck the dust into the cooling fins.

Originally Posted by Alan

GordoB,
How do you like the Radius Master, good / bad.
Sag 180 sorry for diverging the thread a bit. Thanks.

Alan in case you don't hear from Gordo: The Radius Master is a really good unit that works as advertised. The only hassles I've noticed is the three smaller rollers can be hard on belt joins round their tighter radius and the small ball bearings those rollers use wear out quicker than larger diameter wheels.

SAG 180,
Thanks for the info mate, considering have a go at one. On your question, the Makita hand held belt sanders have a graphite sheet between the sole plate and belt, seems to work well.

Originally Posted by Alan

GordoB,
How do you like the Radius Master, good / bad.
Sag 180 sorry for diverging the thread a bit. Thanks.

To be honest, i LOVE IT!!!

it is the most useful machine i have in my so-called workshop area. As SAG mentioned the tight radius is a real problem for low grade (economy) belts. The ones i use are "Deer Foss" brand (not sure of the spelling) and i have had absolutely no issues at all with them in regards to the small radii diameters that the 'Master has. As for the bearings, after 6 years of moderate-heavy use (used on almost every project / job) they still spin like new.

Im happy i bought the machine when i did, it made life Easier than cake.

GordoB

PS: sorry for getting OT /hijacking the thread partly