# Combine a 2x72 belt grinder & 9" disc ??



## rabler (Jan 3, 2022)

I've been fooling around with building a belt grinder, mostly muddling it over.  Finally decided (New Years resolution) to use it as a project to teach myself FreeCad.  I came up with the following idea, combining a belt grinder and disc sander.  Maybe a boondoggle?  Anyway, thoughts/comments from those who have built one before would be appreciated, on this and the general design issues.  This is obviously not a polished design, but gets the proportions and general dimensions.  Gas spring cylinder and some other basic hardware isn't shown.  9" disc.  Base pivot with a 90 degree table turn on the belt grinder to give an edge sander.


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## silence dogood (Jan 3, 2022)

A hundred years ago machines were belt driven by a common line shaft. There are a lot of combination belt and disk sanders on the market, But I have never seen one that used that type of belt sander.  Go for it.


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## keeena (Jan 3, 2022)

Many belt/disc combos I've seen have the disc direct-drive like your model...should work perfectly fine. I would support both sides of the table. One of my disc sanders has a support on 1 side only and it feels flimsy. Since the paper is adhesive it could be handy to make 3-4 discs for dedicated grits. If your sander is going to be VS (VFD): you might be able to use a diamond disc on it for slow speed honing carbide.

Speaking of: get a good brand of sandpaper. The cheapo no-name brands stick worse than a worn out post-it note.

That all said: I have 2 belt sanders have built-in disc sanders (8" and 12" IIRC) and I never (as in: ever) use the disc side. But YMMV.


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## rabler (Jan 3, 2022)

keeena said:


> I would support both sides of the table.


Problem is a back side support makes the grinder belt captive, so changing it gets messy

Yes, vfd on 2 HP motor.  I wondered  how useful the disc sander is for most people, your comment on not using it is hlpful.


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## keeena (Jan 3, 2022)

rabler said:


> Problem is a back side support makes the grinder belt captive, so changing it gets messy
> 
> Yes, vfd on 2 HP motor.  I wondered  how useful the disc sander is for most people, your comment on not using it is hlpful.


GP about the belt changes. Would a center support be possible in your design? Or a quickly removable table like some of the belt table designs?


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## mikey (Jan 4, 2022)

rabler said:


> I wondered  how useful the disc sander is for most people, your comment on not using it is hlpful.



I had a disc on my belt sander and took it off. The disc was useful for wood but not so much for metal and it was a hassle to change the stick on paper if I needed a different grit. You also need a table in front of the disc for it to be useful. Personally, I wouldn't do it but that's me.


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## mksj (Jan 4, 2022)

I do not think that the layout is a good combination unless it is has its own base. I think it would be a bit awkward to use with the disc so far back. That being the case, I have a small bench top unit that I use both the disc and belt and find it handy for small stuff, I plan to upgrade it to a bigger version. But for bigger projects and large metal shaping, I use a Jet J-4200 which is a 6x48 belt and a 12" disc. I almost always use the 12" disc sander as opposed to the belt. It has a good size table that is locked on both ends and very sturdy. The unit is free standing with the motor in the base so very easy to use either sanding unit. Getting good sanding discs/belts they last a long time, I use 60 grit on both. The disc and belt operate at different speeds, disc is primarily for metal.

I think in your case you might be better off with two separate sanders, a fixed speed larger disc sander and a  dedicated variable speed for the 2" belt sander.


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## Lo-Fi (Jan 4, 2022)

I guess my question would be: what can you do with the disk that you can't with the belt?
But it doesn't look like you're making big compromises to have the disk, so no harm giving it a go and seeing how you like it


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## jwmay (Jan 4, 2022)

rabler said:


> I wondered how useful the disc sander is for most people, your comment on not using it is hlpful.


Well then maybe not helpful that I use mine quite a bit. I haven't had a belt on mine more than 3 times in 3 years.
I'm guessing it has to do with what kind of work a person does. Mostly its a deburring station for me. I don't do any stock removal type work except at an actual grinding wheel. No knife making.
But more importantly, it looks like you're cruising right along with freeCAD! That would take me two weeks+ to get something remotely similar done with Fusion. AND my dimensions would be all wrong. Lol
Also..mine's just a 1x36 i think, with an 8" disc.


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## Alcap (Jan 4, 2022)

I recently got a Foley 311   9” disc 1”x42” sander . I put a very course paper on the disc and finer grit for the belt . I find it helpful for me . I do think having a motor with shafts at either end would be better ( easier ) to build , maybe go with a 12” disc . Heres a picture form the internet of one like mine


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## rabler (Jan 4, 2022)

Pondering while reading this:
I will build a stand so accessing both sides is feasible.  I prefer to keep benches clear.  The table for the disc is definitely a compromise, as @keeena noted with asymmetric support. I guess a disc would be useful for slightly larger faces if you are trying to maintain a somewhat flat face, thinking of sanding the faces of a 4x4” cube.  Not sure how much of that kind of work I’d encounter.

The other thing that just occurred to me is that a disc could use  a guard as it will probably otherwise spray grindings in a big arc.  

I think I’ll incorporate the mounting collar for the disc table when I build the central part, but otherwise leave the disc unbuilt. I can easily add it later, just make the necessary parts.


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## C-Bag (Jan 4, 2022)

I have a MultiTool mounted on a 6” Jet bench grinder. It has a wire wheel on the opposite side and the MultiTool has a horizontal 3x36” belt with a 9” disk sander. I took the floppy hard to adjust table off the disk sander. I don’t even leave the belt mounted as it’s crazy easy to take on and off if needed. I have a dedicated tool grinders so the belt is only used for special projects.

I use the sanding disk and wire wheel for shaping and deburring constantly. It is all about what you do and how you like to work I guess.


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## Bi11Hudson (Jan 4, 2022)

Such a device exists at a larger scale for use in woodworking. My personal position is that when you want to build a tool as opposed to buying one,* do it*.  In this case, the erection drawings alone will make it worth the effort even if it never gets built. The building is a way to prove the design. In any case, as a learning experience it would be invaluable. Any use as a working tool in the future is secondary, pure "velvet".

.


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## Pierre52 (Jan 4, 2022)

You may want to contemplate this design by Jer Schmidt that allows the normally vertical belt to rotate 90 degrees.  This is a smart young kid who has now updated his original design and sells a complete build guide and plans for a very reasonable price.




He runs the machine on a VFD so can get very precise control of speed.

I have a separate 12" diameter Disc sander that runs at a much lower RPM than my belt sander.  For that and all the reasons listed above I'm not so sure that disc and belt are compatible.


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## Christianstark (Jan 4, 2022)

Question for the folks commenting on this, and the OP.

I am also starting to plan on a belt grinder per Phil V. plans. Will wind up being 3 x 79 inch belts as the instructions are metric.

The question is, what is the benefit for going 3 phase VFD here? I ask because the area where I will be running this only has 110V now, and although I DO plan or running 220V there, I don't have it currently. I want to keep my grinding area away from my milling and lathe area, so I am planning on using my exterior entry shop for that, and keeping my inside the basement area for chips only. Is it worth the hassle of 220/VFD?

Here is the 110V motor I was considering.



			https://cdn.automationdirect.com/static/specs/ironhorsesprs.pdf


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## dkemppai (Jan 4, 2022)

rabler said:


> I've been fooling around with building a belt grinder, mostly muddling it over.  Finally decided (New Years resolution) to use it as a project to teach myself FreeCad.  I came up with the following idea, combining a belt grinder and disc sander.  Maybe a boondoggle?


Hmmmm,

So, I've been pondering a disc sander attachment for my belt sander. Just a tooling arm with a bearing block and another wheel. Would use a serpentine belt, or industrial J belt to drive it off the existing hardware. Then take it off like any other tool. On the plus side you could actually have to discs. One flat, and one tapered a degree or two. 

Dan


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## rabler (Jan 4, 2022)

Pierre52 said:


> You may want to contemplate this design by Jer Schmidt that allows the normally vertical belt to rotate 90 degrees.  This is a smart young kid who has now updated his original design and sells a complete build guide and plans for a very reasonable price.
> 
> He runs the machine on a VFD so can get very precise control of speed.


I’m doing a pivoting base to accomplish that too, slightly different design but same end result.


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## rabler (Jan 4, 2022)

Christianstark said:


> Question for the folks commenting on this, and the OP.
> 
> I am also starting to plan on a belt grinder per Phil V. plans. Will wind up being 3 x 79 inch belts as the instructions are metric.
> 
> ...


A VFD means adjustable speed, which is not really an option on a single phase motor. Not having used a belt grinder for metal I’m not sure how much benefit that adds, but it is the route I’m going.  There are Teco L510 (and surely others) that will run a 3phase 220v motor on single phase 120V for low HP motors, up to max for Teco of 1HP using the L510-101-H1.  I’m going to 2 HP which would overload a 120V 20a circuit, 220 is required.

I certainly agree with keeping grinding away from machines.


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## dkemppai (Jan 5, 2022)

rabler said:


> A VFD means adjustable speed, which is not really an option on a single phase motor. Not having used a belt grinder for metal I’m not sure how much benefit that adds, but it is the route I’m going.



After having a belt grinder with VFD, I wouldn't be without the variable speed. A majority of the time I run the belts under the maximum speed of my machine. A lot of time it's near 10% or 20%, like 'hand sanding' on a machine. It's really nice for detailed finishing, in that it allows you to work slower. However some ceramic belts perform better with high speed and high loads, so you need to watch the belt selection. 

I would think that 2HP is a good choice. Although it may be hard to use all 2HP on a belt grinder. With a metal drive wheel, there's a good chance you'll get belt slippage before stalling the motor.


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## Christianstark (Jan 5, 2022)

rabler said:


> A VFD means adjustable speed, which is not really an option on a single phase motor. Not having used a belt grinder for metal I’m not sure how much benefit that adds, but it is the route I’m going.  There are Teco L510 (and surely others) that will run a 3phase 220v motor on single phase 120V for low HP motors, up to max for Teco of 1HP using the L510-101-H1.  I’m going to 2 HP which would overload a 120V 20a circuit, 220 is required.
> 
> I certainly agree with keeping grinding away from machines.


Im kind of new to all this. I think my confusion comes from seeing my bench grinder with 110V and variable speed.


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## rabler (Jan 5, 2022)

Christianstark said:


> Im kind of new to all this. I think my confusion comes from seeing my bench grinder with 110V and variable speed.


I'm no expert.  My understanding is VFDs, changing the frequency of the AC sine wave, is the modern approach for larger motors.  Older technology, and small motors are often DC motors that are controlled by voltage.  Stepper and servo motors are another option, more expensive, that require sophisticated controllers.


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## xr650rRider (Jan 5, 2022)

I built a 2"x72" belt grinder using Brian House's plans and even bought the pre-cut metal back before prices went nuts. I used a 2HP 3 phase with a cheap Amazon $89 VFD and it is a metal eating machine. The pre-cut pieces made it a very easy to build project. I also have a 12" disc grinder that I bought from Harbor Freight for maybe $120 and it works well. I'd rather have them separate machines but then I already own both. The disc grinder is the go to for doing stuff like shaping recoil pads for guns. If you use the 2" for knives shaping/sharpening or where you need to change belts quickly, I don't think a disc would be practical. I added a buffing attachment to the 2" grinder with dual buffing wheels but it's driven by the belt and if your not careful, you can cause the belt to jump off the drive and is a pain in the arse. It really needs a different drive belt but I haven't found one yet.


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