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2x72 grinder discussion

Tom Kitta said:
Main issue is tracking. It has tendency to work fine multiple times and then just throws the belt off.

Heck I can do multiple things for like 20 min of use and then suddenly it throws the belt off!
Click to expand...

Belt tension will do this, as well as the tracking adjustment wheel not being in the same plane as the drive wheel

I believe the belts stretch slightly as they are used, I don't see any way to take that up automatically in your grinder, that could be cause for it to throw the belt

And I could be wrong but it looks like the tension wheel is not in the same plane...often the thickness of the adjuster mechanism is forgotten about and the adjuster wheel ends up further out than the drive wheel, I think that may be part of why your tracking wheel is tipped down so far from level

Ive experienced both problems, the second I was able to move the tracking wheel closer to the same plane as the other wheels. That fixed belt throwing 95% of the time
 
skippyelwell said:
I got the basic machine assembled today and made some sparks fly, I saw immediately that 1725 rpm is really not going to cut it. Should have gone with the 3400 rpm motor or 3 ph.
Still, it's usable for the moment.
I haven't made all the other attachments yet but for now will just build the adjustable angle table, the XY table and the magnetic chuck.
The last pic before it gets dirty.
Click to expand...
We have the plans for belt sander as well going to start project soon
 
Finally finished the whole project, Jer's Gen 2 2x72 belt grinder. I pulled the 1725rpm motor off and replaced it with a 3400 rpm motor the other day and got the high heat epoxy spread over the magnetic chuck.
It is a pretty great design, I found one omission in all 5 of the plans so not bad at all.

The linear bearings and rails cost $500 cnd, had I known that at the start I probably would not have built the x-y table and mag chuck.
IMG_1607.JPG
But now that I have them I can see how useful it will be, the mag chuck really holds steel on well unless you start trying to remove too much metal on one pass.
Here is the xy table,
IMG_1977.JPG
You do have to do some delicate tweaking to get the xy table rolling perfectly square to the belt.
The xy table with the mag chuck,
IMG_1978.JPGIMG_1979.JPG
The photos below are of the first test piece of 1/8" steel plate I tried to polish up, I'm sure I'll get better at it.
This is 80grit,
IMG_2002.JPG
120grit,
IMG_2003.JPG
220grit,
IMG_2008.JPG
Then I tried the coarse Scotch Pad like belt, the scratches at the bottom of the test piece are from me applying too much pressure the belt pulling the work piece partially off the mag chuck.
IMG_2014.JPGIMG_2016.JPG
And the rest of the attachments.
IMG_1980.JPG
 
Tom Kitta said:
So the X / Y table is to have some kind of semi precise surface grinder?
Click to expand...
Yes, no where near as precise as a Surface grinder but as you can see from the last test piece pic, it can get you in the ball park of being ready for polishing.
Polishing may be possible with a 2x72 belt of some kind but I'm starting to explore those possibilities.
Knife makers can do some beautiful finishes with these machines.
 
skippyelwell said:
Yes, no where near as precise as a Surface grinder but as you can see from the last test piece pic, it can get you in the ball park of being ready for polishing.
Polishing may be possible with a 2x72 belt of some kind but I'm starting to explore those possibilities.
Knife makers can do some beautiful finishes with these machines.
Click to expand...

Yeah I have home build grinder but a fixed table - I also have surface grinder and T&CG. I discovered it is important to have good belts.
 
skippyelwell said:
Finally finished the whole project, Jer's Gen 2 2x72 belt grinder. I pulled the 1725rpm motor off and replaced it with a 3400 rpm motor the other day and got the high heat epoxy spread over the magnetic chuck.
It is a pretty great design, I found one omission in all 5 of the plans so not bad at all.

The linear bearings and rails cost $500 cnd, had I known that at the start I probably would not have built the x-y table and mag chuck.
View attachment 64115
But now that I have them I can see how useful it will be, the mag chuck really holds steel on well unless you start trying to remove too much metal on one pass.
Here is the xy table,
View attachment 64117
You do have to do some delicate tweaking to get the xy table rolling perfectly square to the belt.
The xy table with the mag chuck,
View attachment 64118View attachment 64119
The photos below are of the first test piece of 1/8" steel plate I tried to polish up, I'm sure I'll get better at it.
This is 80grit,
View attachment 64120
120grit,
View attachment 64122
220grit,
View attachment 64123
Then I tried the coarse Scotch Pad like belt, the scratches at the bottom of the test piece are from me applying too much pressure the belt pulling the work piece partially off the mag chuck.
View attachment 64124View attachment 64125
And the rest of the attachments.
View attachment 64116
Click to expand...
We have the plans for the same belt grinder but we are running with an 220 volt motor , We have been searching were the best place is to buy the 2x72'' sanding belts were did you buy yours , Could you please let me know were the best place to buy them are they available in Canada . Thanks in advance
 
duthie said:
We have the plans for the same belt grinder but we are running with an 220 volt motor , We have been searching were the best place is to buy the 2x72'' sanding belts were did you buy yours , Could you please let me know were the best place to buy them are they available in Canada . Thanks in advance
Click to expand...
Calling @SkookumRob
 
duthie said:
We have the plans for the same belt grinder but we are running with an 220 volt motor , We have been searching were the best place is to buy the 2x72'' sanding belts were did you buy yours , Could you please let me know were the best place to buy them are they available in Canada . Thanks in advance
Click to expand...
I bought the sample kit from Ameribrade, https://www.ameribrade.com/parts-belts/belts
all good quality belts except the 220 grit belts, thin and wore out quickly.
I started with a 1725rpm motor, 230v but have changed over to a 3400rpm, 230v, for my uses I prefer the faster speed.
You'll need at least 1.5hp motor.
If you run into any problems let me know, happy to help if I can.
Start to finish I think I spent somewhere near $2,000 cnd, about twice what I budgeted on but now that it's done I'm pretty happy with it.
I do a lot of machine restorations as a hobby and it has really improved the finishes.
 
skippyelwell said:
Polishing may be possible with a 2x72 belt of some kind but I'm starting to explore those possibilities.
Click to expand...
At work we have some (pretty worn out) 3M Trizact belts, that I like as a step right before polishing. I don't recall the grit we have, but I see them for sale up to an equivalent of 2000 grit.
They're not especially cheap, but my experience is they cut reasonably well right to the bitter end. They're also quite flexible, which can be helpful, depending on application.

For belts, I've bought from Maritime Knife Supply (Nova Scotia) and been pretty happy, but I haven't shopped around extensively.
 
Stuart Samuel said:
At work we have some (pretty worn out) 3M Trizact belts, that I like as a step right before polishing. I don't recall the grit we have, but I see them for sale up to an equivalent of 2000 grit.
They're not especially cheap, but my experience is they cut reasonably well right to the bitter end. They're also quite flexible, which can be helpful, depending on application.

For belts, I've bought from Maritime Knife Supply (Nova Scotia) and been pretty happy, but I haven't shopped around extensively.
Click to expand...
I have two 3m Trizact belts and they are great, very consistent. I think they are equivalent to 200grit but they leave a finer finish than the 220grit belts that came with the belt kit. They look pretty cool too.
 

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