# Horizontal Belt Grinder



## cfellows (Jan 19, 2014)

I did my very first real CNC work today on my newly converted Enco Mill/Drill. Took me over 8 hours of redrawing, reprocessing with CAM and cutting test pieces using MDF until I finally got it right. What a learning curve!







So, on to the real subject at hand. Ever since I first saw one of these, I've wanted one. 






So, I've decided to add one to my small, already crowded shop. The two pieces I started with, above, will hold the small drum on the outboard end of the grinder and be used for grinding very small, inside radius's. The slotted ends will accept interchangeable drum sizes fitted with 7/8" OD x 3/8" ID ball bearings on each end. The overall design is really pretty simple. Here are drawings done in Visio...






 Mine will use a 2" x 48" belt.

Chuck


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## cfellows (Jan 20, 2014)

This is the motor and drive pulley I'll be using for the grinder.  






 It's a 100 volt, DC motor that's rated at 3/4 HP at 2500 RPM.  I have a full wave bridge rectifier installed inside the switch box so I can plug it into 110 volts AC and it runs fine, although it's a bit torquey on startup and will jump pretty hard if not fastened down.  Running at 110 volts, I should get close to 2750 RPM.  The drive pulley is 3.5" diameter x 2.25" long.  This should give me a surface speed on the belt of about 2500 feet per minute.  Higher would be better, but the belts should last longer at the lower speed.

 Chuck


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## Herbiev (Jan 20, 2014)

Looking great Chuck. You'll wonder how you coped without one.


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## rodw (Jan 20, 2014)

Awesome project Chuck. I just bought a linishing belt for my bench grinder. I am not sure if you can get them in the size belt you will use but see if you can also get some scotchbrite belts. Absolutley awesome for alluminium and will polish steel to a high shine...
http://www.machineryhouse.com.au/A36203#


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## cfellows (Jan 20, 2014)

Thanks, guys, nice to see some other folks validating my thoughts that I have a need for one of these!  I'd like to make it convertible from horizontal to vertical so I could replace my vertical 2" x 48" belt grinder, but so far I haven't figured out an easy way to do it.
Today I pretty much finished up the interchangeable roller bracket. 






Still have to bevel the inner edges of the vertical piece to clear the belt and drill the through hole that mounts it to the base, but for now, I'm going to move on to the tension idler assembly. I plan to finish that up before I start on the base/cabinet.

Chuck


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## cfellows (Jan 20, 2014)

Today I got started on the Belt Tensioner / Idler.  






 The vertical piece is 3" x 1.5" x 1.25".  The bottom piece is 3" x 1.25" x 3/4" and is attached to the vertical piece from the bottom with two, 5/16" Socket Head Cap Screws.  Tomorrow I will notch the top of the vertical piece to accept a 3" x 3/4" x 3/4" steel arm that will hold the idler pulley.  It will swivel up and down with an adjustment screw to provide belt tracking.
 Chuck


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## Wizard69 (Jan 20, 2014)

Looks like you are off to a nice start!   

By the way you aren't the only one thinking that such a tool will come in handy!  It is on the list of things to do.


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## cfellows (Jan 20, 2014)

Wizard69 said:


> Looks like you are off to a nice start!
> 
> By the way you aren't the only one thinking that such a tool will come in handy! It is on the list of things to do.


 
 Thanks, Wiz.  By the way, I found some price references from back in 2008... $950 - $1400 depending on options and accessories.  So far, I've spent $2.50 for screws, the rest of the stuff I've had on hand.  May have to buy a few more bearings, but that should be it.

 Here's one last picture for the day.  






 I made a 1" roller.  I plan to make a 3/4", a 1.25", a 1.5", and a 2".   I can also make more as the need arises.

 Chuck


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## barnesrickw (Jan 21, 2014)

Any ideas on a motorized hacksaw?


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## kvom (Jan 21, 2014)

What CAD and CAM are you using? 8 hours seems like a lot for that, but since it was a first part maybe not excessive.  What problems did you have?


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## cfellows (Jan 21, 2014)

barnesrickw said:


> Any ideas on a motorized hacksaw?


 
 No, I owned one once that I had bought and refurbished.  I wound up selling it because I liked my 4 x 6 band saw better.  Never thought about it much since then.

 Chuck


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## cfellows (Jan 21, 2014)

kvom said:


> What CAD and CAM are you using? 8 hours seems like a lot for that, but since it was a first part maybe not excessive. What problems did you have?



 I was using Autodesk Inventor with their new HSM Express CAM plugin.  The main problems were figuring out the navigation through the CAM and getting the pocket to come out the right size.  There are a number of places where you can specify amounts of stock to leave, ostensibly for finish operations or for milling cutters that aren't exactly the specified size.  I was also kind of designing as I went, so I changed the position and length of the slot several times.

 I do have to say that having the CAM as a plugin is convenient.  It's easy to make changes to the part then just reprocess it, all in the same software.  HSM Express is only 2.5D, but I think it will be satisfactory for most of my needs, or at least until I get a little more experience with CNC.  I can see that I have a long, steep hill ahead of me.

 Chuck


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## BaronJ (Jan 21, 2014)

Hi Chuck,

Keep at it !  What you have so far is looking good.  I'm watching with interest.


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## cfellows (Jan 21, 2014)

Thanks, Baron.  This thing is coming together pretty quickly.

 I had a pretty productive day in the shop.  Managed to get the belt tensioner assembly mostly finished.  Here is the idler pulley for the tensioner:











 The pulley started out as a 2" diameter piece of aluminum rod, 2.5" long.  It has a 5/8" hole bored straight through, then a 1/2" ID ball bearing recessed into 1.125" pockets on each end.  A 1/2" bolt will thread into the supporting arm with the jam nut to lock it in place.  I formed the crown on the pulley by turning a 3 degree taper on each end in about 7/8".  Then I used a rasp, a file, and 320 grit sand paper to smooth the transitions while spinning it in the lathe.

 Here's the assembly so far:











 The support arm is hinged on a 3/8" bolt in back with a 5/16-24 Jack Screw for the belt tracking adjustment.

 Still have to figure out the tensioner spring arrangement, drill a mounting swivel hole in the back, and mount a handle on top of the support arm before I can call this part finished.  Then I'll be about ready to start putting this puppy together.

 Chuck


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## BaronJ (Jan 22, 2014)

Hi Chuck,

The photos make that crowning look a little severe.

As far as tensioning is concerned, would a cam arrangement work there ?

Something like a disk with the tensioner mounted offset.


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## cfellows (Jan 22, 2014)

BaronJ said:


> Hi Chuck,
> 
> The photos make that crowning look a little severe.
> 
> ...


 
 I did a lashup this morning with all the parts fired it up.  I think you're right, the crowning is too severe.  I wasn't sure how to calculate the correct slope so I may have to adjust it.

 I don't quite understand the disk arrangement you describe...

 Chuck


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## BaronJ (Jan 22, 2014)

Hi Chuck,

Forget my ramblings about a cam arrangement.  I looked at the video but the spring tensioner simply passed me by.  Then just having scrolled through the post again... Doh.

Sorry :wall::wall:


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## cfellows (Jan 22, 2014)

Getting Close!  Here's the mostly assembled grinder, parked in it's new home.  This space on the end of my Table Saw stand was previously unused and the grinder fits in there nicely.  
















 Here's some photos of the rest of my garage/shop.  You can see it's a bit crowded...











 Now I have to build the spring assembly for the tensioner arm, the backing platen for the straight bit, and the adjustable table assemblies for both the straight part and the end roller.

 Chuck


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## cfellows (Jan 22, 2014)

Here's a short video of the grinder.  Not finished yet, but the running gear is done...

 [ame]http://www.youtube.com/watch?v=KkdHQBYd9Wc[/ame]

 Chuck


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## BaronJ (Jan 23, 2014)

Hi Chuck,

If you think your workshop is a little crowded, I daren't show you mine. 

Its coming along real nice.  That spring clamp and pinching the spring from it is a good idea.  I would add a screw tensioner so that you have some control over it.


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## tornitore45 (Jan 23, 2014)

Great job on building an entire machine from scratch!
A minor point... Household current, today, is 120V RMS but DC motors speed is proportional to the Average value which is 11% lower than RMS or 108V
You lose 1.5V in the bridge leaving ~106V average.
Your motor will be running faster than nominal, but not as much as the 120V/100V ratio implies.


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## Brian Rupnow (Jan 23, 2014)

Chuck--Once you begin to use that, you will wonder how you ever lived without it. A word of caution though---If you do go with a 3/4" diameter nose pulley as planned, you will find that your belts don't survive very long. They don't do well with that tight a bend radius.---Brian


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## cfellows (Jan 23, 2014)

tornitore45 said:


> Great job on building an entire machine from scratch!
> A minor point... Household current, today, is 120V RMS but DC motors speed is proportional to the Average value which is 11% lower than RMS or 108V
> You lose 1.5V in the bridge leaving ~106V average.
> Your motor will be running faster than nominal, but not as much as the 120V/100V ratio implies.


 
Thanks for the info, Mauro, I was a little worried about over-revving it.


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## cfellows (Jan 24, 2014)

Here's today's progress report.  I finished the platen for the straight section and got it installed.







 I also got the spring for the tensioner assembly installed.  I made it simple for starters and can modify it later if it needs to be adjustable.






 And, I got started on the grinding rest for the spindle end.






 The horizontal rest will be mounted on an arm that swings out away from the grinder so the belt and/or spindle can easily be changed.  A 3/4" shaft will provide the hinge mechanism as well as the elevation adjustment so I can use different parts of the belt as it wears.

 Chuck


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## JAndrew (Jan 25, 2014)

Mr. Fellows,

Just wondering what keeps the belt tracking in the center of the rollers? I have a belt sander and the top roller has a thumbscrew to make slight adjustments to the roller angle to keep the belt running centered. And I do mean slight! A smidge on the thumbscrew sends the belt careening off to one side or the other.

Maybe the convex shape of your tensioner roller keeps it tracking...?

Thanks for the posts,
-J.Andrew


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## cfellows (Jan 25, 2014)

JAndrew said:


> Mr. Fellows,
> 
> Just wondering what keeps the belt tracking in the center of the rollers? I have a belt sander and the top roller has a thumbscrew to make slight adjustments to the roller angle to keep the belt running centered. And I do mean slight! A smidge on the thumbscrew sends the belt careening off to one side or the other.
> 
> ...



 Adjusting the socket head cap screw on top of the idler support bar changes the angle of the idler pulley for tracking.  As you said, it doesn't take much!

 Chuck


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## Alchymist (Jan 25, 2014)

tornitore45 said:


> Great job on building an entire machine from scratch!
> A minor point... Household current, today, is 120V RMS but DC motors speed is proportional to the Average value which is 11% lower than RMS or 108V
> You lose 1.5V in the bridge leaving ~106V average.
> Your motor will be running faster than nominal, but not as much as the 120V/100V ratio implies.



RE: 120V RMS:  RMS is the equivalent DC voltage in an AC circuit, so the only loss is the drop across the diodes. The power is the same in a 120V RMS circuit as it is in a 120V DC circuit.


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## chucketn (Jan 25, 2014)

Chuck, great job. You are so creative. i wish I was half as creative! This build should be turned into an article!

another Chuck


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## BaronJ (Jan 25, 2014)

Hi Chuck,

That looks great.  That spring there looks the part.
As they say "a proper job ! "


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## cfellows (Jan 25, 2014)

Thanks, Baron, Chuck.


Today I finished up and mounted the grinding rest for spool end. 











 Some of you may notice the boo boo on the outside edge of the table...  :rant:  I almost cut the notch on the wrong side, but my subconscious jumped in and made me reconsider as I was cutting it.  I'll probably remake it at some point, but it'll have to do for now.
 On to the other grinding rest!

 Chuck


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## barnesrickw (Jan 25, 2014)

Those aren't mistakes, they are angle alignment slots for indexing stuff.  Charge more.


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## cfellows (Jan 25, 2014)

barnesrickw said:


> Those aren't mistakes, they are angle alignment slots for indexing stuff. Charge more.



 That's even better than my idea of "cooling slots".

 Chuck


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## barnesrickw (Jan 26, 2014)

All in the marketing my friend.


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## BaronJ (Jan 26, 2014)

cfellows said:


> Thanks, Baron, Chuck.
> 
> 
> Today I finished up and mounted the grinding rest for spool end.
> ...



Naw.  Slot it and bolt a guide plate on there.  Get the angle right for tool grinding.


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## BaronJ (Jan 26, 2014)

barnesrickw,

You beat me to that idea !  Great minds n all that.


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## cfellows (Jan 26, 2014)

Here is the adjustable bracket for the front grinding rest.  I welded a 5/8" thick block on the front of a 1/4" thick piece rather than try to make it from one solid piece.






 The bracket is fastened to the cabinet with a 1/4" bolt coming down from the top and a nut and washer on the bottom.






 The slot in the bracket arm lets it move from side to side as well in and out.






 The rest itself is (tightly) press fitted onto a 3/4" round pedestal that slides up and down in the bracket.






 So the grinder is now functionally complete.  Everything works and both grinding rests are done.
















 I want to replace some of the plain nuts and/or bolts with handles so I don't have to reach for a wrench when I want to move something.  Then I will post a video showing how everything works.

 Chuck


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## cfellows (Jan 27, 2014)

Here's a video I made today of the finished grinder:

[ame]http://www.youtube.com/watch?v=tkxWFjFUy6g[/ame]

Hope you pardon the videography, it's pretty amateurish.

Chuck


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## Brian Rupnow (Jan 27, 2014)

It looks good Chuck. The ability to change rollers for inside curves is a very nice feature. You may find out that under heavy use, the spring won't be strong enough and the belt will bounce. Of course that will only happen once, and the belt then flies off the rollers. You may want to put a lock down bolt on the spring loaded swing arm. The only other thing I see is that you may want to put a fence /rest somewhere at 90 degrees to the belt travel, so that under heavy grinding the fence/rest will take a lot of the load so the part is not so difficult to hold in place while you are grinding it. I built my belt grinder many years ago for smoothing the edges of flame cut plate brackets when I was building hot rods. Mine has a 4" wide belt and a big old 2 HP motor. I wish now that I had put one of the pulleys right on the end of the motor shaft like you did. I have a v-belt drive from my motor to the drive roller, and that v-belt sucks up a lot of my available power. I made my rollers from 3" diameter solid steel stock, so there is a lot of inertia to overcome when I start it. When I turn the switch on that big old motor, all the lights in Barrie go dim until things get up to speed.


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## barnesrickw (Jan 27, 2014)

Really like home made tools.  Very nice job Chuck.


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## cfellows (Jan 27, 2014)

Brian Rupnow said:


> It looks good Chuck. The ability to change rollers for inside curves is a very nice feature. You may find out that under heavy use, the spring won't be strong enough and the belt will bounce. Of course that will only happen once, and the belt then flies off the rollers. You may want to put a lock down bolt on the spring loaded swing arm. The only other thing I see is that you may want to put a fence /rest somewhere at 90 degrees to the belt travel, so that under heavy grinding the fence/rest will take a lot of the load so the part is not so difficult to hold in place while you are grinding it. I built my belt grinder many years ago for smoothing the edges of flame cut plate brackets when I was building hot rods. Mine has a 4" wide belt and a big old 2 HP motor. I wish now that I had put one of the pulleys right on the end of the motor shaft like you did. I have a v-belt drive from my motor to the drive roller, and that v-belt sucks up a lot of my available power. I made my rollers from 3" diameter solid steel stock, so there is a lot of inertia to overcome when I start it. When I turn the switch on that big old motor, all the lights in Barrie go dim until things get up to speed.



 Thanks for the tips, Brian.  I had already figured I'd need a 90 degree fence to rest things against on the straight section.  Haven't tried any real heavy grinding, but so far I haven't seen any slippage of the belt.

 Chuck


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## Wizard69 (Jan 28, 2014)

cfellows said:


> Here's a video I made today of the finished grinder:
> 
> Hope you pardon the videography, it's pretty amateurish.
> 
> Chuck




Nice video!

Looks like you are well on your way with this machine.


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## barnesrickw (Jan 28, 2014)

The belt adjustment is impressive.


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## rodw (Jan 30, 2014)

Chuck, the video is awesome. What a great tool you have made. I have mentioned them before but if you are working with aluminium, see if you can get a belt something like this :
http://www.machineryhouse.com.au/A48203

Someone told me about these and I find it is on my machine most of the time. Expensive I know but they last longer so they are not that expensive to run.


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