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  #1  
Old Sat 22 September 2007, 10:31
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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I have been working on the design of my angle iron trimming machine and decided to make a wooden prototype to test the concept. It is a combination of Geralds original idea and a sample on J.R.'s thread.

I felt it would be difficult to move a 3m (10ft) length of angle iron past a fixed grinder and still keep it under control. My moving grinder attachment rides on alwayse ball units (a steel ball riding on many smaller balls held captive in a cup). I had originally thought of using normal bearings on edge but was concerned with the tendency that they would have of moving off line if not travelling 100% parallel to the angle iron. With these ball units I will be able to apply side pressure as well as longitudinal pressure.

The prototype was made of some ply I had laying around in the garage so excuse the odd bit of paint and pen marks - I will be making a production model with steel as the ply has too much flex.

I am using a Ryobi angle grinder as its what I had available but then it comes with a hidden advantage. The gear head has metal threaded bushings that were originally used to mount the guard, this makes it easy to mount to the holding plate. It has three M4 threads and one M5 thread. I have used SS cap screws to mount the holding plate.

The four set bolts allow me to adjust the height of the cutting disk off the table as well as allowing me move it higher to mount a grinding disk to polish the top of the cut angle iron.

I dont like that bit of cutting disk exposed at the back so the production model will have a modified holding plate to cover the disk.

I did not have a sample piece of angle iron at hand so I have shown the assembled unit next to a length of timber instead.
Attached Images
File Type: jpg 01 trim parts.jpg (103.6 KB, 1513 views)
File Type: jpg 02 grinder head.jpg (39.6 KB, 1500 views)
File Type: jpg 03 mount plate.jpg (36.8 KB, 1500 views)
File Type: jpg 04 with disk.jpg (40.4 KB, 1500 views)
File Type: jpg 05 base.jpg (37.8 KB, 1500 views)
File Type: jpg 06 complete unit.jpg (97.6 KB, 1507 views)
File Type: jpg 07 bottom view.jpg (120.2 KB, 1499 views)
File Type: jpg 08 mounted ball unit.jpg (43.3 KB, 1490 views)
File Type: jpg 09 working position.jpg (42.0 KB, 1500 views)
File Type: jpg 10 model no.jpg (39.8 KB, 1493 views)
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  #2  
Old Sat 22 September 2007, 14:44
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
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Don't try to cut deep, I found this out the hard way. The cut will heat up and the 1/16" disc will suffer loss. The first 12' rail I cut down took about 4 disc, the second took almost as many. When I started the 8' rails I worked smarter by taking longer faster passes. The 8' rails took 1 disc each and a lot less time. Go easy when the disc cuts through, this is another place where you use up a lot of disc.
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  #3  
Old Sat 22 September 2007, 22:00
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Yes, you don't use a grinder like a table saw. A grinder touching red-hot metal just chews up the disk. Use an oscillating motion that moves the disk to cold metal all the time. (Those chop-saw cut-off grinders are terrible at chewing up disks)
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  #4  
Old Sat 22 September 2007, 22:19
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Beautiful craftsmanship Alan. I like the idea of moving the tool rather than the angle iron. I moved the iron and it was a real bear. I started out cutting the 8 foot pieces in case I screwed one up it would be cheaper to replace it. When I started cutting the 12 footers, I switched to a new silicon spray and it ended up creating a gooey mess that actually made it harder to push the steel. I didn't figure that out until I had cut for a couple of hours. I just assumed the 12 foot lengths were much heavier than the 8 foot lengths.
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  #5  
Old Sat 02 February 2008, 15:32
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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Progress - AT LAST

I made some mods to the grinder skate to fit my Ryobi grinder but it has ended up putting the grinding wheel in a different position to the standard item, this means I have to drop lower to the angle to get the full grind. I may just extend the slots so that the grinder holding plate is able to move further across. ( this means I will also have to extend the cut out in the base plate as the grinding wheel will foul the edge)

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  #6  
Old Sat 02 February 2008, 19:34
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Nice rail cutting tool...I sure bet it glides nice.
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  #7  
Old Mon 04 February 2008, 02:21
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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That rail cutting tool does move sweetly, I have just closed the holes in the top of the ball bearing units to stop the grinding dust getting in there.
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  #8  
Old Sat 09 February 2008, 14:31
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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Z Slide Assembled

Started cutting the Y axis angle iron for the rail - the cutting jig works great but seems to use disks at a rapid rate, went through 3 1/2 disks to cut just one rail, and no I wasn't pushing too hard. When the disk is new, it cuts with a good flow of sparks, but once past halway, the sparks get less and the disk wears at a much higher rate. I was using the thin (1mm) disks from both Norton and Klingspor. The Norton ones wore down much faster.

As I didn't have any more disks on hand and the closest supplier is over the Mountain, I decided to call it a day and join the Kids in the pool (temps over 30 deg C today, but predicting thunderstorms for tomorrow)
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  #9  
Old Sat 09 February 2008, 15:13
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
The good cutting disks are by Pferd - ask them for the thin Inox (Stainless Steel) disks.
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  #10  
Old Fri 15 February 2008, 15:11
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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Pferd disks rule, cut the second Y rail tonight with only one disk and it stayed cutting all the way down to the centre. Will do the bevels tomorrow.
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  #11  
Old Sun 09 March 2008, 12:46
skypoke
Just call me: Chuck
 
Port Aransas
United States of America
Belay all that...we got it done. As others have said, the selection of grinding discs is of paramount importance. I ended up ordering the Pferd discs. We used a fixed grinder arrangement to cut down and ended up milling on the table saw. Lots of fantasies during the process of a Mechmate carrying a grinder and making rails!

Chuck
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  #12  
Old Thu 01 May 2008, 13:51
Kobus_Joubert
Just call me: Kobus #6
 
Dalview
South Africa
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Cut the Y-Rails down using the top part of the skate. Used about 5x Pferd 1mm thick disks to do the job.

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  #13  
Old Thu 01 May 2008, 22:35
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Kobus, how long did it take you to cut all the rails down?
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  #14  
Old Fri 02 May 2008, 01:38
Kobus_Joubert
Just call me: Kobus #6
 
Dalview
South Africa
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Cutting the rails was one of those jobs that I thought would be a pain. So much that I got a quote from the company that did my laser cutting. Luckily for me he came with a mad price (almost the same as all the Mamba parts) and I had to supply my own steel this time. This forced me to do it myself. And what a piece of cake. Firstly I thought of using my table saw with a cutting disk. Did a short piece of rail, but this was hectic and too dangerous to my liking. I eventually clamped the angle iron onto my table saw top and grinded piece by piece using the table saw as a nice straight reference surface. All in all it took no more than one hour to do one rail. Much easier moving a small grinder than a BIG LUMPY piece of steel.


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  #15  
Old Fri 06 June 2008, 08:18
lunaj76
Just call me: Justin #24
 
Littleton, (Colorado)
United States of America
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Cutting rails to 1.1 with grind head top plate.

We ordered 2.5X1.5X.25 angle for the rails instead of the recommended 2.5X2.5X.25. Reason: only 1.725 of working height between bottom of grind head top plate and work surface (grinder is Bosch 1710). By using 2.5X1.5X.25 you get more life out of the cut wheel because the uncut rail will completely slide under the bottom of the grind head top plate. Am I making any sense? We used the pferd cut wheels and only used a few wheels cutting 40' of rail to height.

Justin
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  #16  
Old Thu 26 June 2008, 20:58
Johannescnc
Just call me: John
 
Hannover, DE
Germany
Cutting the angle iron down with grinder and abrasive disk

This post moved from http://www.mechmate.com/forums/showthread.php?t=810

I have been following this thread for a while and wonder what the life expectation is from the rails to warrant the purchase of tools like these for one machine build... When I buy a tool I either buy a cheap one for short term use or a good one that I will use often. But, I have not had the fun of cutting down 40-50 feet of 1/4" steel yet either... So I would welcome the thoughts on this method or using a disc grinder... John


I like the look of this.... inexpensive use of a common tool...

Last edited by Gerald D; Thu 26 June 2008 at 21:33.. Reason: add photo
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  #17  
Old Thu 26 June 2008, 21:21
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I will try and assemble some reports of folk who used this method into this thread. Please tell me where there are relevant posts in personal (or other) threads that I can copy to this one.
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  #18  
Old Fri 27 June 2008, 02:47
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
For the guys experienced in moving the grinder against the static rail (which I feel is superior to my "trash can" test), what are your thoughts on turning the rail around, to reference the grinder on top of the long leg of the angle iron? Realise that is a narrow face, and that clamping will be in the way, but I believe it will be easier to get a consistent rail height. . . . . .
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  #19  
Old Fri 27 June 2008, 03:01
Kobus_Joubert
Just call me: Kobus #6
 
Dalview
South Africa
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Could be an idea to go that way. Even on my FLAT table saw surface and the angle clamped with 2 big G-Clamps or is it C- clamps, I still noticed a small variation...1-2 mm over the total length...maybe my bolts wore down quicker than anticipated?
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  #20  
Old Fri 27 June 2008, 03:16
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
With the way that Kobus and Alan clamped the rail down, a bit of dirt between the rail and table would make the grinder cut too low. Also, the angle iron bows when that edge is cut off - it might be bowing away from the table.
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  #21  
Old Fri 27 June 2008, 06:16
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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I drilled my rails first, then cleaned it all up before screwing it to the MDF support board (checked to make sure all was very clean) My variation over the length as measured with a digital vernier was no more than 0.2mm - more than acceptable I think for a "garage" process. I did not notice any bow, but if it had the mdf running surface would have bowed with it.
Also by running on the support (support flush with bottom of rail) ensures that should one run over some dirt or grinding dust build up or lift the skate slightly, the result would be a rail that is slightly oversize - i.e. easy to still bring it down to the correct size. If one runs the "skate" on an upside down rail and there is loss of contact will the running surface, the result would be a rail that is lower than required - i.e. can't be fixed without grinding the entire length down to that height.
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  #22  
Old Fri 27 June 2008, 07:09
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I don't mean upside-down, I mean with the long leg pointing towards the grinder instead of away.
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  #23  
Old Sat 28 June 2008, 01:29
hennie
Just call me: Hennie #23
 
Roodepoort JHB
South Africa
Cutting The Rails On Sliding Table

This will be my attempt at cutting the rails to the required hight.
With luck the hight of the disk was exactly what is specified.
The length of the sliding table of the saw will allow me to cut the rails a little longer than what is required so I will have some steel left for grinding the angles.
I can move the guide on the right to adjust the cutting depth of the disk.
I will make mdf blocks to tighten the angle iron on the sliding table by using the slots in the table.
(only had this little bracket to pass the idea as I have not cut the angle iron to size.planning to do it next weekend.)Will post pic`s as I do the cutting.
Attached Images
File Type: jpg picture 006-qpr.jpg (32.6 KB, 1494 views)
File Type: jpg picture-qpr.jpg (41.0 KB, 1496 views)
File Type: jpg picture 007-qpr.jpg (38.1 KB, 1507 views)
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  #24  
Old Sat 28 June 2008, 02:40
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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Nice idea Hennie...but, remember that the cutting process produces a large amount of fine steel dust and it would be a sin to gum up all the precision moving parts of that (what looks like a quality Felder) panel saw with abrasive dust. I did mine inside my garage and I am still finding fine black dust on some shelves and hardware boxes, if it gets damp, it turns to rust. You may also experience difficulty in applying the correct amount of side pressure on the disk, its not like a sawing action where the blade sticks through the steel, more like a slow groove thats gets progressivly deeper as you slide the steel/grinder backwards and forwards past each other.
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  #25  
Old Sat 28 June 2008, 02:47
Alan_c
Just call me: Alan (#11)
 
Grabouw (Western Cape)
South Africa
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Quote:
Originally Posted by Gerald D View Post
I don't mean upside-down, I mean with the long leg pointing towards the grinder instead of away.
Oh! That might be tricky as the surface is not very wide, it will be fine for the front end of the grinder support, but the back end will still need some other means of support independant of the angle. If these two surfaces are not 100% in plane the reslutant cut will have slight changes in the angle of the top surface, although that might not make a difference to the final product.
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  #26  
Old Sun 29 June 2008, 00:02
hennie
Just call me: Hennie #23
 
Roodepoort JHB
South Africa
Hi Alan

Did look into the dust side of things also (would pay Jack overtime to help me ), on every second pass he can clean the table with the extractor.I will also use tape to cover the opening where the blade of the saw is 50 mm wide sellotape (did stick it to the saw but pic doesn`t show).

I should have the balance of the lapp cable by end of this week then I can confirm total cost for them.
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  #27  
Old Sun 29 June 2008, 01:12
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Hennie, I am nervous about your method. The dust is one issue (grind dust is highly abrasive by definition, and it gets in everywhere - 3+ meter radius). But the other issue is the fact that the rail curves as you split it. How will you make sure that the curved rail is lying flat to your slider?
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  #28  
Old Mon 30 June 2008, 02:07
hennie
Just call me: Hennie #23
 
Roodepoort JHB
South Africa
Option 2 for me.

I have a offcut length of formica top 32 mm thick 3550 mm long.
I would make a support table for this which have to be level (straight over the full length).In the centre I would have my bench drill to drill the holes for the rails and a guide at the back.( will make it during the week )
Question
Gerald if one drill 3,5 mm holes into the rail where the fixing holes would be and use chipboard screw to attach the rail to the formica would it help in some way with the bowing of the steel as one cut the rials down?
(once completed with cutting & grinding one can drill the holes to 12 MM)
32 mm formica top attached to a support table should be stable enough to give nice hight and straight rails and steel are attached over the full length.
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  #29  
Old Mon 30 June 2008, 02:22
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Hennie, that sounds a lot better. (A chip screw happily grips in a 6mm hole). You are heading for the method used by Alan - he also screwed the rail to "wood" before cutting it down with his karretjie.
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  #30  
Old Mon 30 June 2008, 08:46
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
A video from Brazil:
http://www.kapbrasil.com/trilho.wmv
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