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Grinder build pics

Here's the link again if you don't want to go back to the first page ;)

 

Patrick, the build is coming along very well! I was a little confused at seeing the motor mount without the motor on it, I just wasn't visualizing it properly. But with the entire thing standing, it's looking great (and a Lot taller than I thought). 132" is looong. Hope the parts arrive soon, and sorry to hear about the computer. I'm always a little afraid of lightning for that reason.

 

John

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Grinder build pics

Here's the link again if you don't want to go back to the first page ;)

 

Patrick, the build is coming along very well! I was a little confused at seeing the motor mount without the motor on it, I just wasn't visualizing it properly. But with the entire thing standing, it's looking great (and a Lot taller than I thought). 132" is looong. Hope the parts arrive soon, and sorry to hear about the computer. I'm always a little afraid of lightning for that reason.

 

John

I wanted it really tall. I want the upper contact wheel about chin height. Part of my improved posture while working regiment. The computer survived Hooray! It just needed some jiggles. I am very relieved :)

 

I worked on the electrics all day today. The motor cables had to be shielded in metal conduit. The wireing diagram for the VFD was flat out wrong which made things difficult figure out. Something was lost in translation from the German manufacturer... I have to change out the romex feeding my subpanel from 10/2 to 8/3 to get the proper 240v feed...Now it looks like I will have to install a separate ground for the sub panel as the VFD requires an earth ground. Still lots of work ahead of me.

Patrick B)

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I have used them and they work fine, though they have tended to be chippy (IME) on the edges. Currently I have a piece of granite tile on mine. It has stayed flat, the edges are still good and it's been in place for over a year.

 

Geoff

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I have used them and they work fine, though they have tended to be chippy (IME) on the edges. Currently I have a piece of granite tile on mine. It has stayed flat, the edges are still good and it's been in place for over a year.

 

Geoff

Granite hu! B)

Very tough stone...

Thanks for the feedback!

Patrick B)

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Nice work on the grinder. You can see the thought put into it's planing and building, I really like the tracking mechanism. What size drive wheel are you going to use?

 

Zeb

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Nice work on the grinder. You can see the thought put into it's planing and building, I really like the tracking mechanism. What size drive wheel are you going to use?

 

Zeb

 

Well I had a choice from my stock of 6" or 4" I put on the four yesterday as the motor is a 3450 RPM already and I don't want the extra SFPM that the 6" would give me. The VFD will take care of the rest...

Patrick B)

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I use a ceramic platen liner and I like it very much. That granite tile idea is one I need to try, though!

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Broke my first tap on this project...Almost made a hundred. Added side strap on tool arm today. Added a relief channel for the arm lock. Added a threaded plate for the Lock and of course added the lock. Finished bolting in the tension assembly. More exciting I ran the motor! The VFD is powered up and working great. First test was with default mode which works well in mid to high frequency but has low torque at low frequency. I programmed the motor specs into the unit and changed it to another type of mode more appropriate to the task (it has a lot of options and modes). Now The torque is there all the way down to 180 rpm (That is as slow as the unit will allow). The display started out showing Frequency, but after programming, it is giving RPM instead. The Drive wheel is just a hair over 1' in circumference so 1 RPM gives 1 SFPM roughly. So Now if the display says 500(rpm) you can read it as 500 SFPM which is kind of cool B)

All that is left is the stand, The tension method, and a nema 4 like enclosure for the VFD.

 

DSC00226.JPGDSC00229.JPG

DSC00230.JPGDSC00232.JPG

 

Patrick :)

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Broke my first tap on this project...Almost made a hundred.

Patrick :)

 

Damn,

 

That's a whole lotta tappin'.

 

Nice looking grinder Patrick.

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If I have this right, your tension is added by the wheel attached to the two vertical rods?

 

It's certainly a different build and looks very solid!

 

I like the idea of bolting it all together as it allows the possibility to add and change bits later.

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If I have this right, your tension is added by the wheel attached to the two vertical rods?

 

It's certainly a different build and looks very solid!

 

I like the idea of bolting it all together as it allows the possibility to add and change bits later.

 

I am calling the bottom wheel the carriage. I have three different designs to tension the carriage. The first one I going to try will take advantage of the fact that my tensioning system works with gravity rather than the traditional against gravity. So I simply going to install ballast on the carriage and a simple way to lift it to change belts.

I like bolts also, and I sold my welder a year and a half ago. So bolts is all I have right now, but I do like the fact that I can change the design anytime I want, add or subtract things easily.

I am getting close to finishing this thing for now. I will have videos of it running when I do. I am waiting on a filter and fan for the VFD box for now.

Patrick B)

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Grinder Update.

Ok well I have been testing the grinder out as is, though it is far from finished. The first thing that I noticed was that if I press really hard on the belt she would jump towards the motor. It would track really good then with a certain amount of pressure and no warning it just jumps! Ok some careful attention to the drive wheel alignment cured that problem completely. I built in adjustments for this so it was easy to correct.

Second thing I noticed is that even with abnormally high belt tension I can make the belt slip on the drive wheel fairly easy. The current configuration only has the belt in contact with 1/4 of the 4" drive wheels surface. It is simply not enough. A different arm configuration would help improve this. Using a triangular configuration rather than a square up top would help too.

 

Third thing. The surface feet per minute, I sorely missed the mark. I got the numbers right I just thought for some reason that I did not want it going faster than 3500 SFPM. After doing some home work I figured out my previous grinder which I was comfortable with was doing 5000! I also found that Some baders are set up to go much faster.

 

SO to get two scoops of icecream with one cone I decided to make a larger drive wheel. It will give me more surface area for traction and increase my SFPM. I got a deal on a 7" diameter drop of 6061 and decide to make the largest wheel I could get out it. I will get roughly 6000 SFPM from this and I can slow that down with the VFD when needed. I spent today turning it out. My lathe is only made for 5" stock so it took most of the day to complete. It is slow going with very light cuts.

DSC00462.JPG

DSC00463.JPG

 

You can see the whole process HERE

 

Patrick :)/>

Edited by Patrick Hastings

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Ooh, pretty! :lol:

 

Have you thought about maybe putting some masking tape on the drive wheel to increase friction? It would help with the belt jump too.

 

If my house ever quits trying to fall apart so I can get some cash saved, I really want to go the VFD route. :rolleyes:

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Ooh, pretty! :lol:/>

 

Have you thought about maybe putting some masking tape on the drive wheel to increase friction? It would help with the belt jump too.

 

If my house ever quits trying to fall apart so I can get some cash saved, I really want to go the VFD route. :rolleyes:/>

 

I thought about it, but I want to see how well the extra surface area does by itself then add tape if needed. The jump is a total non issue once the wheel if perfectly aligned. I could not make it jump or even shift slightly once I adjusted it.

The VFD is simply awesome.

Patrick

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I have a Ton of the Brass bushings you used I have been working on many uses for them and I now have yet one more to do a grinder Man this is one bad Ariss Grinder thank you for sharing it .

 

Here is the one I have been working on http://www.metalwebnews.com/manuals/knife-grinder.pdf

 

Sam

Edited by Samcro

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I have a Ton of the Brass bushings you used I have been working on many uses for them and I now have yet one more to do a grinder Man this is one bad Ariss Grinder thank you for sharing it .

 

Here is the one I have been working on http://www.metalwebnews.com/manuals/knife-grinder.pdf

 

Sam

 

Thanks Sam, That is a very comprehensive set of grinder instructions!

 

Today I made a steel hub for the new wheel. I pressed fit it into the 1" hole in the new drive wheel. It also friction fits on the motor shaft. It has a through hole and is threaded on the end so I can simply put a bolt into the hub to pull it off the motor if needed.

My first experiments show the crown to be slightly too pronounced The edges of the belt are floating above the wheel. So I need to go back and make it more subtle like the wheel before it. I thought the crown should be higher, but now I see why it should not. And why is that? because it reduced the contact area quite a bit and I am still not getting as much traction as I think it should have. So I am glad its easy to remove hehe. The 4" wheel I took off this morning was also friction fit and was a real pain to get off :o

Patrick :)

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Just a thought, but can your design bring the two platen idler wheels closer together. A little shorter platen would probably cause less drag/friction, and you can get the belt to wrap with more contact percentage around the drive wheel. I've tried, but not an expert or pro, various ceramic tiles (no granite) for backing on the flat platen and I believe the thinness and possibly less friction of the various high heat glass may be a slight advantage. I haven't run into chipping or breakage. Mostly, I just wanted to mention that I appreciate you taking the time to share the project.

 

Take care, Craig

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Just a thought, but can your design bring the two platen idler wheels closer together. A little shorter platen would probably cause less drag/friction, and you can get the belt to wrap with more contact percentage around the drive wheel. I've tried, but not an expert or pro, various ceramic tiles (no granite) for backing on the flat platen and I believe the thinness and possibly less friction of the various high heat glass may be a slight advantage. I haven't run into chipping or breakage. Mostly, I just wanted to mention that I appreciate you taking the time to share the project.

 

Take care, Craig

 

Well I have been testing and measuring to find out just why these issue are occurring. I am not an engineer, but once I have something in front of my I can generally figure out how to fix it. so I have been looking for the real problems. I know that Baders often have less surface area in contact with the drive wheel than I do on my design. So there are other factors at work here. The larger wheel I installed in effect did as you suggested. It moved the drive wheel top 1.5 inches higher than the top contact wheel. and did the same relative to the tension wheel. So I have almost 1/3 of the wheel in contact with the belt now. The 4" only had 1/4. So I have plenty of contact area. The Crown it definitely too much. It is slightly less than 6 degree included. I think I am going to go with about half that.

Some tape on the wheel to test crown heights also brought the traction up significantly. I can't make it slip with the tape on there, Tracking is good, but there is still a belt jump if you bear down really hard. that should not be there.

I found an issue that is contributing to the problem. The arms that extend downward have a bit of flex to them when the grinder is under tension. You can't really see it unless you put your eye right up on one and sight down it. Or rather the belt. The belt is being bent like a banana side ways. Its subtle, but it is enough to put side tension on the belt and stretch it unevenly. So no matter how perfectly I have it aligned there is always a force side loading it which make the belt jumpy. Earlier on I thought I might have to have a brace come down from the main body to the bottom of the arms. I was willing to forego it, but now I see that it would have resolved or minimized the issue of arm flex. So I will be adding a big structural member back into the design. More info and pics as I go...

Patrick :)

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One kind of subtle design theory that one of the high end grinder makers is using, I believe to manage that belt jump and "banana" effect is to put the tracking wheel closer bottom. Supposedly, that's where the belt is under more tension and responds better to tracking control than on the top where resistance against the platen may cause less tension on the part of the belt that's coming off the drive (tracking) wheel. Not picking on your design at all, just came to mind when you described your issues. I'd agree that stiffer and beefier couldn't hurt if you suspect flexing.

 

Thanks again for taking the time, Craig

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One kind of subtle design theory that one of the high end grinder makers is using, I believe to manage that belt jump and "banana" effect is to put the tracking wheel closer bottom. Supposedly, that's where the belt is under more tension and responds better to tracking control than on the top where resistance against the platen may cause less tension on the part of the belt that's coming off the drive (tracking) wheel. Not picking on your design at all, just came to mind when you described your issues. I'd agree that stiffer and beefier couldn't hurt if you suspect flexing.

 

Thanks again for taking the time, Craig

 

 

I have been putting a lot of thought into studying it. I believe that there are two zones they occure most strongly between the point where the work contacts the belt and the drive wheel. As the drive wheel turns it is pulling the belt through the resistance of the work so this is the higher tension side. On the other side leaving the drive wheel and being fed to the work is the lower pressure side. I made my drive wheel the tracking wheel thinking to help avoid the top wheel design issue. I would put it on the bottom wheel so that it acts as both tension and tracking, but it is on the freaking floor hehe. It makes sense to me though that that could offer improved tracking. Bader space savers track from the contact wheels which is similar to tracking from the drive wheel. If I had a way to adjust the tracking from the bottom wheel that would be ideal , but its just not convenient DOH...

I am re-cutting the drive wheel this weekend. Will post results on performance changes...

Patrick B)

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Just build it.

beltgrinderctrack.jpg

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I really like your concept for this grinder and it is definitely a well built machine and thanks for the tutorial.

I believe if you add a tracking wheel between your drive wheel and your top idler wheel you can control the tracking much better at that point,just a thought.

I can't wait to see this finished and running!

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My Grinder Build is under way I will not Jack this thread ,However I will post one as I am building it .

 

Sam

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