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  #1  
Old Thu 04 January 2007, 14:32
Arthur Ransom
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Ideas & Experiments with different rail styles

I am a woodworker and have little experience/tools in the metal arena. Also my mill will end up about 14? long. Milling rails is beyond what I have the equipment for. Why couldn?t I use ? cold rolled rod ($12 USD for a 20? piece) attached to a 1? by 1/8? base with the 12mm rollers? I suspect that with my welding skill level warping might be a problem. A possible solution might be 3M?s epoxy part # DP460NS. 3M suggested it but the data sheet doesn?t mean anything to me. Can some one translate it for me?
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  #2  
Old Fri 05 January 2007, 02:06
Manjeet Singh
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Arthur, Isnt it better to use drawn rod instead of cold rolled. As drawn material is as cheap as cold rolled and have better shape and more straightness than rolled one.

Manjeet
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  #3  
Old Fri 05 January 2007, 04:13
Arthur Ransom
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Didn't know that. Actually I can get stainless for $39 USD for a 2M piece so material cost is not a factor. The main question is the use of adhesices instead of welding thold the rod.
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  #4  
Old Fri 05 January 2007, 04:44
Bob Cole
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Arthur:
Something to consider.
If it is possible to have a shallow groove milled into the mounting surface of your mill rails that would be perfectly parralell to the edge. This would provide a "bed" or guide to either epoxy or weld your rod into that would position the rail perfectly, and provide slightly more surface area to epoxy or weld to.
I have looked at epoxy welding and have done some on aluminum with great results. With a finished tensil strenghth of upwards of 20,000 lbs per sq. in. It should prove to be a reasonable solution.
Check with some of the leaders in the epoxy field, and you may find what you need.
here is one source I have used. www.lord.com
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  #5  
Old Fri 05 January 2007, 05:02
Arthur Ransom
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How about exact product? How about using it in structural components? If it will work I could see it as a great solution for those that dont have a welder or on places where warping could be a problem. Should a seperate thred be started?
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  #6  
Old Fri 05 January 2007, 07:57
Gerald_D
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I am not going to support a rod welded/glued to a flat bar - too many variables and risks.

There is no problem in butting two (short) angle iron rails together to form a longer rail, provided that the foundation is very sturdy. Such a butt joint does not need to be welded, glued, keyed or dowelled.
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  #7  
Old Fri 05 January 2007, 07:57
Bob Cole
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Art:
In order for you to get the "BEST"info you should contact the company directly. That being said I just talked to one of their application specialists. They suggested using their 400 series adhesives for our bonding applications. They offer 3 different speeds if you will. 403 is the fastest, 406 is intermediate, and 410 gives you the most time time to set up your job. All three series end up with the same tensil strength once they are fully cured. Usually less than 24 hours.
They offer complete brochures and samples are available from distributors. You need to do some research for yourself as to where to buy.
I am ordering samples today.



P.S. I just noticed Gerald's responce to this part of the thread. I understand his position regarding deviating from "his" build plans, and respect that position completely. If you are not welding your parts, then you ARE NOT building the MechMate per Gerald's original concept.
regards,
Bob C.
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  #8  
Old Fri 05 January 2007, 08:04
Gerald_D
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"If it is possible to have a shallow groove milled into the mounting surface of your mill rails that would be perfectly parralell to the edge..... " Bob, if you could do that, why not just put the V on top of the angle iron (same machining issues) and you are done without glueing on anything further?
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  #9  
Old Fri 05 January 2007, 08:12
Bob Cole
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Gerald:
I was just addressing Arts' question. I agree about the milling of the edge on the angle iron rail.

Regards,
Bob C.
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  #10  
Old Fri 05 January 2007, 10:15
Arthur Ransom
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I agree that deviating from the original plans is not a desired option. Gerald has done an exceptional job and I haven't see anything nearly as well designed. In looking at MechMate it didn't take me long to reaize that he had designed something much better than I could come up with an dthe more I understand the plans the better I love them. That said he needs to reaize that there are, me included, many of us that don't have his knowledge, skill and equiptment and need to come up with another solution. In my case I need a mill that will allow me to do wood columns 24" by 12'. The only other solution is a 200K comercial machine. For my need I suspect that the MechMate with modifications is a better solution without considering the price differenc. The original plans obviously won't work But modification to meet the need is fairly simple. I will need to swing 27" to end uo with 24" finished diameter and rotation speeds will be less than 100 RPM on large balanced columns.
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  #11  
Old Fri 05 January 2007, 11:50
Gerald_D
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I don't mind folk applying some lateral thinking, but I might chose to remain silent when alternatives are tossed around. If these alternatives divert the main focus, then I could move them into other threads or delete them. Sorry that I am so "narrow-minded" on this, but I have other projects as well and need to limit my time to do only the MechMate "essentials".
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  #12  
Old Fri 05 January 2007, 21:04
Manjeet Singh
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Hi All, Gerald is right if we keep discussing alternaives then we could divert in other direction rather than making something and there would only discussions like on cnczone. more and more people discuss there rather then to build their ideas.
Manjeet
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  #13  
Old Sun 07 January 2007, 06:00
Arthur Ransom
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I have received a tool rest to test from a manufacturer that uses epoxy to bond a 1/4" tool steel rod to 3/16" steel base. Apparently I have developed a reputation in my area of turning. Stresses will excede anything Mech mate will place on rails. Any way I will move this discussion to CNC Zone.
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  #14  
Old Mon 26 February 2007, 22:26
Loren Gameros
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Hello, I am having a bit of a hard time sourcing a company to machine/grind my rails. Can anybody make a recomendation. I am in the Western United States. Thank You.
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  #15  
Old Wed 25 April 2007, 15:29
Arthur Ransom
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Real world versus theoretical world

In the theoretical world V rollers will have a larger bearing surface if they roll perfectly aligned on a V track. In the real world that the MechMate machine lives in does it really matter that the edge of the track is not a V? Off the shelf angle iron has a slightly rounded edge so the V rollers would have two relatively small bearing surfaces with a high load PSI but is it a high enough load to round it over or wear fast enough for us to care? Most of us work in wood which expands or contracts daily and I expect is in excess of the MechMate tolerances. Anyone ever tested their machine to see what tolerances it will hold? Our tolerances are sloppy compared to the guys that work in metal and isn?t plus or minus .01? more than adequate? Just wondering if we aren?t beating a dead horse on the V track issue.
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  #16  
Old Wed 25 April 2007, 23:00
Gerald_D
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Arthur, you are so right on this! There is a very mistaken belief that CNC = accuracy or tight tolerances. The typical woodworker works with nothing better than a tape measure or steel rule and he needs a CNC to give him speed and relieve him of repetitive tasks - he does not need a machine that gives him a whole new toolbox of sensitve measuring instruments! A "crudely" built MechMate satisfies the typical woodworker requirements. Put some more effort/money into a MechMate and you get something of a precision that matches your input - but, you will probably have to buy some finer measuring tools then.
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  #17  
Old Thu 26 April 2007, 07:55
Arthur Ransom
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Along this line when building a machine for wood why couldn't I just take 1" angle iron and use the 90 degree as my rail? Weld tabs every 6" for bolting it down and straighting?+
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  #18  
Old Thu 26 April 2007, 08:08
Gerald_D
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1. You will have nothing to attach the rack to.
2. Welding every 6" will warp the rail quite a bit.

But, if you lay a 2.5" x 3/16" flat bar down and then glue/weld/cskscrew/dstape a 1" x 3/16" angle iron on its end, run the roller directly on the tip of the vertical leg. Load 400 pounds on the gantry, roll it up and down a hundred times and you'd have a pretty good rail.

Your local plate-bending shop might even bend you a nice "L" - but they seldom do. Their tools are normally worn in the center and you see the middle 4 ft of a 12 ft bend is bent more at the ends than in the center. ShopBot used bent 3/16" rails till recently with size 2 wheels
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  #19  
Old Thu 26 April 2007, 11:01
Charlie T
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Ive wondered about running right on the back side of angle aswell. Ive got my rails done, but for some people this might work good. Just a little hand sanding and its smooth. Flat bar with angle laying on it ,both legs down, point up. With that comes other problems (like everything)with the mounting of it. I dont know the best way to mount it.
The design is great as it is now, but its hard to watch so many strugle with this.

*sidenote*
MY rails are so nice that when I run the bearing on them (by hand) I can feel dust on the rail I whipe it with my finger and its as smooth as glass.
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  #20  
Old Sun 20 May 2007, 10:35
Art
Just call me: Art #2
 
Lancaster,Texas
United States of America
Decided to jump off and try my idea using 1/4" rod to make the rails. I have a the rods under considerable tension and siting on the flat base. It will be several days before my 3M DO420 epoxy arrives so hopefully they will strech and straighten even more though from what I can measure they are straight. I will bond a 2" section in the center and let that cure then bond the rest of the rod and release most of the tension before the epoxy cures. In theory I should have a very straight rail. Then flip over the piece and bond the rack in place. The picture is a test piece that I welded up to test the idea.
Attached Images
File Type: jpg rail.jpg (91.4 KB, 1937 views)

Last edited by Art; Sun 20 May 2007 at 10:47.. Reason: add pic
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  #21  
Old Sun 20 May 2007, 12:34
J.R. Hatcher
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Wilmington, North Carolina
United States of America
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Art, try drilling some holes in the flat stock, center of where the rod will be, then clamp and weld the rod from the underside through the hole. should make cleaner sides.
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  #22  
Old Wed 11 July 2007, 05:19
Art
Just call me: Art #2
 
Lancaster,Texas
United States of America
Successful rail idea

All ideas discussed so far on rails are either too expensive or a dirty, time consuming job. I tried using .25" rod but couldnt get it straight enough. Then it struck me. Flip the angle 90 degres and you have the proper angle for the V rollers. I flipped mine clock wise but see no reason that counter wise wouldn't work. Works great!
See http://www.turningaround.org/4_axis_mill.htm for complete details. As a point of interest the arc cut in the part that the V rollers bolt to is not centered on the motor pivot point and has to be enlarged to allow a .5" stepper motor shaft. I still need to clean up the cabeling, install the brush on the dust collector foot and a few other small details but otherwise my mill is back up running with the Mechmate gantry.
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  #23  
Old Wed 11 July 2007, 09:02
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Art, I don't see a picture where the arcs are involved (not even sure that I see rotated angle iron) on your linked page?
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  #24  
Old Thu 12 July 2007, 17:33
Art
Just call me: Art #2
 
Lancaster,Texas
United States of America
Off center arc

Attached is the side frame showing the arc that is not centered on the motor pivot point. I had to widen the cut out because the motor shaft wouldn't fit. Because the .5" angle iron rail is lower than the original plans the arc had to open in the bottom. Also I redid the picture on so the rail can be seen better.
Attached Images
File Type: jpg side.jpg (31.5 KB, 2199 views)

Last edited by Art; Thu 12 July 2007 at 17:37..
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  #25  
Old Thu 12 July 2007, 23:42
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
That arc that you cut longer is not for the motor shaft. That arc is for the heads of the capscrews that hold the geared motors on. (You can see the arc lining up with a "surplus" screw hole in the motor swing plate)

The motor shaft runs below (not through) the plate that you modified.

Interesting pics at your revised page! How is the performance (rigidity etc.) doing for you?
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  #26  
Old Thu 12 July 2007, 23:47
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
PS. Your gas spring is upside down. The thick body of a gas spring must always be to the top. There is some oil in there, and it must lie against the critical neck seal if you want any life out of that system.
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  #27  
Old Fri 13 July 2007, 11:47
Marc Shlaes
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Cleveland, OH
United States of America
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Art,

Innovative! Gerald, on all hatchback cars in the US, the thick part of the gas spring is always on the bottom. I'm guessing that affected the thinking. Is that why they always seem to wear out? You see countless older cars where someone is using a stick to hold it up while they load up at the Home Depot. I had a minivan once that went through a bunch of them.
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  #28  
Old Fri 13 July 2007, 12:08
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
The thick part of the hatchback spring is at the bottom when the hatch is open, but in the closed (natural) position the thick part should be at the bottom. Our first gas spring has a year's service on it and it is still okay. I know this is a bit experimental for the CNC application, but the alternatives are not pretty. Imagine the alternative to a gas spring on a hatchback.....
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  #29  
Old Fri 13 July 2007, 14:39
WTI
Just call me: James
 
Detroit (Michigan)
United States of America
G, are you saying that the gas spring in this bandsaw is correct, or incorrect?

Our thick part is on the bottom, as pictured.

http://www.harborfreight.com/cpi/cta...emnumber=93507
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  #30  
Old Sat 14 July 2007, 00:03
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
James, we have that same saw. That is not a gas spring (not pre-charged with high pressure nitrogen). It is a standard oil-filled system with a little control valve that regulates how fast the oil flows from under the piston to the top. It only regulates the speed at which the saw drops. You have to lift the saw entirely by hand - there is no counter-balance effect.
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