Call me an idiot, or a genius - upgrading benchtop 4x36

nateman_doo

nateman_doo

Joined
Sep 16, 2015
Messages
158
I don't have a fancy belt grinder. I do have a 4x36 benchtop sander.

A thought occurred to me to modify it so I can flatten out forged material and turn it into "flat stock" for later use on my CNC.

I found out I can separate the sander into the motor section, and the "platen" section we can call it:


By reproducing the platen:



All I have to do is use a 3/8, or 1/2" thick precision ground top plate, and some angle iron, and I can reuse the rollers, and mate the whole structure to these 4 holes on the machine:


I should now be able to sand close to 24" long billets flat enough to put them on my CNC. I know that it will put more stress on the motor, but if I dont press as hard on the billets, it should be about the same load that I put on it normally. Also the motor has thermal safeguards against some stupidity.

What do you guys thing? Brilliant, or Bonehead. The "upgrade" will be less then $100.00
 
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I'll never say bonehead to using something you already have an adapting it but I'm not sure it will get it flat enough to CNC straight on unless you wanna pass over it with a facemill or a fly cutter in which case why not just do that in the first place? I dunno maybe I'm missing something.
 
You can jb weld a piece of glass over the platen area instead of steel. It's cheaper, flatter and wears much more slowly than steel.
 
J. Doyle said:
You can jb weld a piece of glass over the platen area instead of steel. It's cheaper, flatter and wears much more slowly than steel.
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I am beginning to like it here. I like the way you think.

I would be worried about accidental drops, plus the original platen is just bent sheet metal, and it didn't wear out too badly of the almost 10 years I have had it.
 
redbate said:
I'll never say bonehead to using something you already have an adapting it but I'm not sure it will get it flat enough to CNC straight on unless you wanna pass over it with a facemill or a fly cutter in which case why not just do that in the first place? I dunno maybe I'm missing something.
Click to expand...

My CNC is home made, all aluminum construction. It was never designed to mill steel, let alone damascus/tool steels etc. It does do it, but it isn't happy about it. trying to get a piece of steel flat isn't easy, so I am hoping this will do 90% of the job so perhaps a single pass with and end mill over the surface will get it to where I like it.
 
Just finished it. will do a further test tomorrow:
[video=youtube;-7dxyOyaegc]http://www.youtube.com/watch?v=-7dxyOyaegc[/video]
 
Curious what type of belt, has a smooth joint that won't give me that tapping. This is a general purpose 36 grit belt from McMaster.

So for less than $100, I converted it into something of a faux surface grinder. There is a 4x24 x 0.375" ($62) slab of precision ground low carbon steel under the belt as the platen surface.
 
What kind of CNC do you have? How big is it? You might consider making your own 2x72 and possibly milling it out of aluminum, using your CNC.
I just started ordering parts to build a 4x4 cnc router myself.

As for cutting down on the belt splice bump, you can try knocking it down a little more with something like a diamond file or dia-pad.
 
I have one of those and use it to flatten handle blanks. I can drag the motor to a stop with just light pressure so I have to go slowly. That's on a piece of handle material 1.75" wide by 5.25 long. I imagine larger pieces are going to tax that motor substantially.
 
TRfromMT said:
I have one of those and use it to flatten handle blanks. I can drag the motor to a stop with just light pressure so I have to go slowly. That's on a piece of handle material 1.75" wide by 5.25 long. I imagine larger pieces are going to tax that motor substantially.
Click to expand...

it takes substantial pressure from me to stall my motor. Don't think I ever stalled it. perhaps yours is either different, or has a bad motor?
 
confirmed it does work. Its slow removal, but it does work. Grinds it quite flat. So far I can only find aluminum oxide multipurpose sanding belts. nothing like ceramic or zirconia alumina (but I only just started looking)
 
Made some adjustments, and it found more torque. No idea why, but I don't care. Doesn't bog down the motor and removes material nicely.
 
Check out pops or trugrit, they might have belts available.
If they don't have them listed, give them a call. I have found both companies to be personable and very willing to work with their customers.

Worst case scenario, depending on how your tracking is, you should be able to run 2"×72" belts and there are plenty available for you in that size range.
 
Added this small bracket, which kept the additional weight distributed.

One of the benefits of having a CNC. Making small things like this on the fly. It simply is just pressed on with hand pressure, and just sits there. Doesnt need to be bolted down.

And here is where it rests:


I can take just about anything and push it against the belt. Runs smoothly and still eats away material with very little bogging down.
For under $100 it has been a VERY wonderful upgrade to be able to grind flat long items.

I may upgrade the motor at some point, but for now, I will just leave this as is until I see some significant shortfalls.
 
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