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  #1  
Old Sun 20 January 2008, 05:58
Atifeh
Just call me: Nader
 
Tehran
Iran
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V-Rail profiling device - an alternative skate design

Hello Gerald and all,

Based upon the works done by Gerald, JR, Gmessler and others I came up with a design which I would like to share the concept for further improvements/redesign. A zipped MDT6 file and some screen captures are attached for further discussion. The dwg file will be updated as its progress.
Most of the design, you are familiar with. Some differences are:
An outrigger is devised, 3.5 mm off the iron angle curvature and with sufficient distance from the rail's bolt holes, assembled with the related washers and bolts. It should also provide sufficient room for C-clamping. Although the center distance between the outrigger and the rail crown bearing is about 25 mm, it should provide more support to avoid rocking hence vertical pressure could be exerted. The outrigger will be lifted and lowered proportionate to the rail crown bearing since they are both assembled on one cam mechanism. The 180 degrees rotation of the cam handle will result in 3 mm of displacement. The rail is assumed to be cut from 70x70x7 mm angle iron for a size of 70x30x7 mm.
The inner rolls are KR32 needle bearing which are used as belt idlers (they are quite cheap). Its width is 14 mm compared to the 12 mm of 6004 bearing. These rolls are fixed in their location and the clamping will be done by 2 nos of 6004 bearing as per JR's design.
In order to grind both sides of the rail, the angle grinder assembly will be indexed 180 degrees and no special adjustments are required regarding the rolls locations. Correspondingly the handle location will be changed to the opposite side. This would provide a 2 point grip (the handle and the angle grinder itself).

There are some deficiencies in the drawing which will be completed later; so far they are:
The angle grinder neck and fixing bolts are not drawn since they might vary for different makes. I could not get their dxf files through Tracepart or even their own websites and I don't know if they are willing to submit their drawings to us. It would be a good idea to gather a database of different angle grinders as once Gerald started, with their relative flange holes and neck diameters and heights.
The distance between the angle grinder plate and the grinding wheel itself is not actual. Once established, this will change the hole locations on the side braces and the related holes on the side plate.
By using lobe holes different angles could be set for grinding. I found some Russian bearings having 75 degrees grooves which I can send the pictures if you are interested.

Thanks
Nader
Attached Images
File Type: jpg 1.jpg (33.1 KB, 1302 views)
File Type: jpg 2.jpg (33.8 KB, 1291 views)
File Type: jpg 3.jpg (27.1 KB, 1286 views)
File Type: jpg 4.jpg (27.5 KB, 1283 views)
File Type: jpg 5.jpg (27.1 KB, 1291 views)
Attached Files
File Type: rar Railv1.rar (158.1 KB, 120 views)
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  #2  
Old Sun 20 January 2008, 08:54
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Nader, the best way of clamping the rail for grinding, is to drill the holes and screw it to the rail base. In other words, no G-clamps. This will allow the white "outrigger" wheel to run at the far edge of the angle iron and provide much more stability against "rocking".

However, I don't know if "rocking" is a real problem at all. Maybe you have a solution for a "problem" that does not exist? Someone did report a rocking problem, but his skate (and grinder) was very flexible. Those who have used a stiff skate (thicker metal) and sturdy grinder have not reported problems with rocking - they say they don't need the outrigger wheels.
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  #3  
Old Sun 20 January 2008, 13:24
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Grinder rock not noticable

I just finished grinding my machine rails a few weeks ago. With a properly adjusted Mamba skate, I had no noticeable rocking. The eccentrics locked the skate firmly to the rail for machining and kept it in plane. Additionally, I did mount the rails to the machine and grind-in-place.....TONS of room.

My 2 cents
Sean
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  #4  
Old Mon 21 January 2008, 00:48
Atifeh
Just call me: Nader
 
Tehran
Iran
Send a message via Yahoo to Atifeh
Thanks for the response. I will omit the outrigger section then.
My concern was that if rocking happens then a neat 90 degrees profile might not be attained, producing excessive play on the gantry.
Nader
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  #5  
Old Mon 21 January 2008, 00:57
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
The 90 degree profile is not critical for play either - the roller will always contact 2 sides of the profile. Even if the roller ran on round bar, there will be no play. Some people run the rollers directly on angle iron without any grinding of special profiles.

I do not suggest that we get lazy about making a good 90 degree profile - I simply want to show that a bad profile does not produce any play.
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  #6  
Old Mon 21 January 2008, 04:41
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
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I don't remember where but if memory serves me somewhere in this forum is a discussion around the original skate and rocking. When the skate is adjusted correctly for the thickness of the rail (and they vary in thickness) IT DOES NOT ROCK. May I make a suggestion ..... before attemping to correct problems with the skate ............. use one. jmho (just my humble opinion)
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  #7  
Old Mon 21 January 2008, 05:39
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by J.R. Hatcher View Post
. . . somewhere in this forum is a discussion around the original skate and rocking. . .
here?
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  #8  
Old Mon 21 January 2008, 09:57
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
It was my skate design that rocked and could not produce a good 90 degree surface.

I really didn't want to spend any more time designing a skate and decided to have outside sources make my X, Y, and Z rails.

Rocking shouldn't be an issue if you don't copy my design.

When Tom Edison failed, he said

"Results! Why, man, I have gotten a lot of results. I know several thousand things that won't work."
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  #9  
Old Thu 24 January 2008, 19:09
Marc Shlaes
Just call me: Marc
 
Cleveland, OH
United States of America
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Sean / Gerald,

Is there any additional thought about Gerald's new skate design? I remember Gerald asking if it was safe enough. Frankly, it makes me a little uncomfortable that it has no provision for handles. I certainly don't mind spending just a couple of extra dollars for some handles. The ones available at places like Rockler typically have a 5/16 stud. Two simple tapped holes and it would be done. The plate might have to be widened a wee bit. Since I hope to be doing that soon... Thoughts.?
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  #10  
Old Fri 25 January 2008, 09:12
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Marc,
I didn't show the photo's, but I did put 2 handles on the exposed 5/16" threads on the adjustment plate. NO tapping needed. Plus, not a lot of real estate available on the skate. This made it very nice to push/pull the grinder with both hands. I you look back in the other grinding thread, you will see that Gerald drafted a little drawing showing a handmade version. I just went to ACE hardware and bought 2 for 6 bucks.
The back side of the grinder disc is exposed and I run it without the guard.
A simple guard is possible, I just choose not to install it back when I assembled the skate.
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