Tilting 2x72 build

K

Kevin Powers

Joined
Jul 23, 2015
Messages
411
I've been posting this build on social media and other places since Photobucket screwed over the internet. So this is my first try at posting with a different picture host. Hope it works out.
My design is based on Dan Comeau's open source grinder the sayber OSG. (Thanks D.C.)
I downloaded his DXF files and modeled the grinder in solidworks. Once in solidworks I started changing some things around. I modified the tracking arm to be able to use a gas spring instead of springs. Modified the motor plates to use less steel as I was welding the chassis together instead of bolting. I then shortened the overall height of the grinder to fit my small motor.
Once I was happy with the drawing I had the plates waterjetted by a friend. This project is a better candidate for laser cutting instead of waterjet due to the cost it would be to waterjet. Even though I got it done for free it still took over an hour of cutting. Laser would be much much faster.
Finished model.
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Cut parts
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Mock up with my old stripped EERF in the background. My eerf served me well for almost 3 years but there was much I didn't like about it. Mostly I cobbled it together and cut corners.
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I ordered a 4" tracking wheel and a 5" drive wheel from Chaz at Knifegrinderparts. His products are top notch, his shipping and packaging is awesome, and The prices are great.
Instead of cutting a stack of spacers out of the 3/8" plate I had some 1/2"x2" aluminum flat bar laying around. I milled it down, and drilled and tapped it for 1/4-20 cap screws.
Once I mocked it up I decided to ball mill the spacers to allow dust and debris to find a home and allow for the tool arms to slide easy. It works great.
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One of the changes I made to the design was adding these slots. They don't really serve a purpose I just think they look cool. I even kept the lock locations and think it's a cool detail. I guess it will make things easier to blow out.
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Now onto the tracking arm.
One thing I absolutely hated about my eerf grinder was the tracking mechanism and the floppy arm. I like that the sayber had a double shear mount for the arm pivot. On the eerf if I tightened the bolt to get rid of the floppy arm, it wouldn't pivot anymore.
On this build I turned a couple pieces of delrin to go on each side of the arm. Then turned an aluminum spacer to take up the remainder of the gap between the frame plates.
No more floppy floppy
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Then I turned a knob out of the rest of the chunk of aluminum I used as the spacer for a tracking adjustment knob.
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Since I hurried in the design and cutting out of the grinder pieces (about 5 hours total) I didn't have the overall height of my gas shock. When I drew the assembly I only drew one tab to mount it. I plan to modify the drawing and include an upper mount on the tracking arm and a little more height to the arm so the arm sits level when in use. I decided to put a tab on the chassis because the mounts you get from McMaster carr really suck. This way the gas shock is more rigid and less floppy.

Things left to do:
Get a new motor as the old one has a bent shaft.(prying stuck drive wheel 3 years ago)
Make a pull handle for the tracking arm.
Align wheels
Make new tooling arms/work rests.
Finish the tilt lock.
 
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Lookin' good!

I built mine out of heavy gage square pipe, and I've been wishing that I did it this way. Not so I can tilt, but because every thing on mine is not quite square.

I think it would be easier to keep everything in line better with this design.

Alas. Oh well mine works, just not the best!

Nice looking grinder!
 
Looking good - I used aluminum for my grinder which works really good "IF" the threaded holes for tool arm clamp bolts use heli-coil inserts. The aluminum threads wear out fairly quick.
 
Kevin Powers said:
Now onto the tracking arm.
One thing I absolutely hated about my eerf grinder was the tracking mechanism and the floppy arm. I like that the sayber had a double shear mount for the arm pivot. On the eerf if I tightened the bolt to get rid of the floppy arm, it wouldn't pivot anymore.
On this build I turned a couple pieces of delrin to go on each side of the arm. Then turned an aluminum spacer to take up the remainder of the gap between the frame plates.
No more floppy floppy
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I used two jointed 6201 bearing on my tracking arm for that same reason .Tracking arm is 19mm thick steel and bearing are 20mm and they protrude just enough to tighten up that 12mm. bolt ..... Now is solid as rock , free pivoting and absolutely no floppy-floppy ;)
UTIpXEO.jpg

On part that hold tracking wheel I use three jointed ball bearing ....again for same reason .......

2evABit.jpg
 
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I know I already commented on your Instagram post but dang Kevin I'm loving this grinder set up. Direct drive, dual tool arm slots, 90 degree tilt with minimal footprint, heck I'd be interested in picking one up if you ever made a run of them. Great work man.

Blessings,
Joshua
 
Went to the surplus yard and could only find a 3450 1hp motor. My disc and old eerf have 1750 motors. Needless to say I'll have to dig into programming the vfd and turn it down. The pot on the vfd is too touchy right now and I'm a slow grinder. I don't need to be grinding at 9000 SF/m.
The metal yard didn't have any new tooling arm material so I flipped mine and used the other end to reconfigure the new mounts. Not pretty new aluminum but it works. Got the platen and wheel lined up. Tomorrow I'll get the small wheel tool arm setup.
https://instagram.com/p/Bc3Sg8zlpDxSYPTLAH9fZIUiCy8JZgLYuVKjP40/
 
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Randy3000 said:
Fun fact, I was a developer for solid edge.

Edit
Oh, I see you're using solid works :mad:
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After being a fabricator and welder for the last 20 years, and now 2 years of cnc and solid modeling, my world has changed. I can't believe I did it the hard way for so long. I literally have wasted thousands of hours on projects that would've never worked.
 
Kevin, that's a good looking grinder - and runs smooth!!! I really like the looks of it. balancing a coin really shows just how smooth it is. I LOVE direct drive grinders - just no comparison to the 3 pulley belt drive I had first.

You said the coin fell over at 8500 SFPM? You're using a 3450 rpm motor? Is that a 9" drive wheel or perhaps you're using the VFD to double motor speed to 7000 rpm? A 3.82" drive wheel will have the RPM equal to SFPM belt speed. I like a 4" drive wheel that puts the belt speed just slightly above the motor RPM.
 
Ken H> said:
Kevin, that's a good looking grinder - and runs smooth!!! I really like the looks of it. balancing a coin really shows just how smooth it is. I LOVE direct drive grinders - just no comparison to the 3 pulley belt drive I had first.

You said the coin fell over at 8500 SFPM? You're using a 3450 rpm motor? Is that a 9" drive wheel or perhaps you're using the VFD to double motor speed to 7000 rpm? A 3.82" drive wheel will have the RPM equal to SFPM belt speed. I like a 4" drive wheel that puts the belt speed just slightly above the motor RPM.
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Yes it's a 3450 and my first at that RPM. It's all the surplus yard had in 1hp. I have a 1750 on my disc and old belt grinder.
5" drive wheel is new as well.
Honestly I don't know if it fell over from vibration or wind. This thing is smoking fast
 
Yep, at that speed before the coin felt over, it's a smooth grinder! BTW, with a direct drive at 3450 RPM with a 5" drive wheel, the belt speed is 4516 SFPM range. As you said "This thing is smoking fast!!". :thumbsup:
 
Ken H> said:
Yep, at that speed before the coin felt over, it's a smooth grinder! BTW, with a direct drive at 3450 RPM with a 5" drive wheel, the belt speed is 4516 SFPM range. As you said "This thing is smoking fast!!". :thumbsup:
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That's at 60hz, not 120 right? It fell at about 100hz
 
At 100 hz it should be around 5750 rpm, so with 5" wheel that would be around 7500 SFPM = smoking fast!

BTW, I would try to hold any motor a tad less than 5,000 RPM due to motor windings 'n bearings. Not saying it won't be smooth at that high RPM (your balanced coin shows it is smooth), but motor life would be somewhat reduced running in the 7,000 RPM range. With a 1750 RPM motor you can run 200% wth no problem because that's only 4500 rpm

For the test you ran - no problem and it really shows how smooth your grinder is. I balanced a coin at 4,000 RPM and felt good about that :)
 
I really like the build. Dan and I did a lot of back and forth when I was designing my grinder at the same time he was designing the OSG Sayber. Hindsight being 20/20, I'd have built the sayber.
 
Kevin McGovern said:
I really like the build. Dan and I did a lot of back and forth when I was designing my grinder at the same time he was designing the OSG Sayber. Hindsight being 20/20, I'd have built the sayber.
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Yeah dans plans are extremely thorough. I'm not even finished with the build yet but I used the grinder yesterday. It was so nice to have none of the issues I had before. Now I have to try and re teach myself how to grind without anticipating belt movement.
 
Kevin Powers said:
Yeah dans plans are extremely thorough. I'm not even finished with the build yet but I used the grinder yesterday. It was so nice to have none of the issues I had before. Now I have to try and re teach myself how to grind without anticipating belt movement.
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Hey, I know this is an older Post , but I'm wondering if you did DXF files for this build? I like the compact style and motor placement. How has it been running for you now that you have over a year on it?
 
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