#31
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Next steps: I'm working on the rails first, so I can use the main beams as my work surface. I've cleaned one of the four rails with my belt sander to remove any mill scale off the bottom surface.
The plan is to use my handheld steelmax saw to cut the rails to height, and then the skate to grind the angle. I've got the parts needed to make a better fence for the steelmax, with an extra spring-loaded guide to keep the saw in position. Oh, four rails, I hear you ask . I need 60' of rail (roughly) for x and y. I figured it was cheaper and simpler to buy four 20' angles, and machine the lot of them. Then when I'm done, the best 60' ends up on the table. That gives me 20' to figure out what I'm doing . |
#32
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Melissa,
Speaking from experience if you use the steelmax saw to cut your rails to the "right" height you will still have wavey imperfections in the height of the rail section. After many trials, I ended up cutting the rails down with a steelmax with height .85 to .120 higher than required...then set up the grinder in a horizontal fashion (like you were cutting them down) and surface ground the height with a little more precision. A couple of passes and I had a nice surface to start from. The key to the "skate" is the rails are top referenced on the grind and if your not right from the start you will get an imperfect result. Sean This Last edited by domino11; Wed 13 August 2014 at 10:04.. |
#33
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Thanks, Sean. I was afraid that would be a problem.
At this point, I'm probably going to cut the rails down with the angle grinder, and use the steelmax for other parts of the build. It does seem like a waste of effort to saw the rails down, and then still have to grind them. Might as well grind and be done with it. |
#34
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Melissa,
The "trick" if there is one is to use the proper narrow kerf abrasive cutting blade on your grinder. If you search the forum, you will find great success using the stainless steel type of cutting wheel. Then, still making a "polishing" pass on top set up square with either the standard grinding wheel. Good luck...it goes pretty quick, I've done it with 3 machines with great success. Last edited by domino11; Wed 13 August 2014 at 10:04.. |
#35
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I did manage to find a 20-pack of Porter Cable thin stainless-cutting wheels on sale a while back, so I'll go with that. We'll see how they stack up to the Pferd wheels .
I have the first rail clamped to the beam, ready to cut. I notice there's a bit of a dip along the beam, due to the floor (or my sawhorses) not being totally level. I'm guessing that this is of no concern due to the short length of the skate, and the rail will still end up OK. Am I correct? |
#36
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Well ,
The cutting is bottom referenced to the table your cutting on. My suggestion is level a 4' section (or use a table saw top) and cut small perfectly level sections at a time. Use a lot of clamps to maintain the angle iron against the table is really secure. That imperfection you suggest "shouldn't" show up in the tool bit, but it might depending all conditions. I worked in smallish sections. 6 to 8' at a time because I had a nice, really level work table to cut on. As Greg would say "garbage in, garbage out...." Sean |
#37
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Not much progress to report (paying work has been getting in the way... good problem to have!).
I did install a network webcam in the workshop, so I'll have a complete set of photos of the build process, which will eventually turn into a time-lapse video. Here's where the build stands so far: main beam leveled on four sawhorses, first rail clamped and ready to be cut to 28mm. |
#38
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Making sparks!
Finally got all the bits together to start cutting the rails. I welded an M10 nut onto the skate, to attach the grinder's removable handle. That made it much easier to handle the skate, especially when the cutting disk started to grab and jam in the slot.
The first rail is cut to height, and just needs a polishing pass to clean it up a bit. About 1.5 hours to cut 20', and used up three cutting disks. |
#39
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I especially like the plastic bag on the wall phone!
NIce photo's. |
#40
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That whiteboard will be as pitted as the lunar surface, by the time you've gone through 20 grinding wheels!
From the spark-trail length, grinder rpm, and wheel radius, can you estimate the camera's shutter speed? |
#41
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Rails are cut to height now. I really wish I'd used my steelmax for the rough cut (.1" higher than needed). The grinder with cutting disk worked great... until it was through in some places, not in others. Then it would grab the edge and yank itself into the slot (and almost out of my grip ).
I wasn't about to change my process after doing three rails (and screw up the fourth one!), so I just forged onwards. Ah well, that stage is done. On to grinding the angles tomorrow! |
#42
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I made some modifications to the skate for grinding the angles. The exposed disk had me worried... 1 second of inattention and I'd be visiting the hospital .
I saw the photos of the laser-cut parts with the built-in guard, and figured I'd just weld something quickly to approximate that design. I cut a 10" piece from the off-cuts of the rails, made a few relief cuts to be able to bend it, and welded it to the bottom part of the skate. Then I used a cutting disk to remove the connecting part from the old piece. End result: easier to change the disk, and much safer to hold . |
#43
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Nicely done Melissa! Your moving along nicely!
Last edited by domino11; Wed 13 August 2014 at 10:06.. |
#44
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Yeah, I see Instructables like this every day... Step 1. Weld some stuff onto your hand tools...
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#45
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grinding rails
Started on grinding the rails today. The first rail is done. After glazing one disk very quickly, I opted to use a sanding disk backed up with the grinding disk. The trick is to make 4 cuts in the abrasive disk (around the centre hole), to help it conform to the dish shape. Next, press it into that shape with a vise. Then, it was actually possible to spin on the centre retaining nut on the grinder.
Here's a fun animated gif of me grinding the V (click for the bigger version) : |
#46
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Charlie Chaplin, colourized and with safety gear. Do they make bowler hats with built-in face shields?
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#47
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Finished grinding the second rail tonight. Here's a couple of photos of the v-wheel sitting on the rail. The grind was done with a 36-grit sanding disk mounted on top of a normal 1/4" grinding disk.
Also pictured is my magnetic sweeper, which is probably the most useful tool I've purchased for this build. It's just magical how it clears the floor, all without using the vacuum cleaner! |
#48
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magnetic sweeper! Great idea....
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#49
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Looks kinda fuzzy!
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#50
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and how do you clean the magnetic sweeper ?
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#51
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Heat it past the curie point??
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#52
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Well done Melissa
Last edited by domino11; Wed 13 August 2014 at 10:06.. |
#53
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Oh, that's easy! You use an even BIGGER magnet!
(just kidding, there's a handle on top to retract the magnets inside the aluminum body) |
#54
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(In case anyone's wondering, any resemblances between that sign, and the piece of equipment that got Paul Lauterbur his Nobel Prize, and the scrapping of said equipment, are purely coincidental. Although that magnet could have easily lifted an entire Mechmate.)
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#55
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A new milestone: dead grinder!
I reached a new milestone on my mechmate today -- a dead grinder .
I think I let out some of the magic smoke yesterday, when it was running rather hot. It ran OK this afternoon, then started making a awful rattling sound. It appears that part of the magnet assembly has come loose inside the body. Ah well, good thing I bought a 2-pack of grinders on sale so I can just swap grinders on the skate, and finish the last rail. |
#56
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...yep, that's about par if you push the little grinders to hard. Once the lamination inside gets to hot, the metal parts fall apart.
The part of the DIY experience is usually killing at least one tool along the process. |
#57
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Melissa mentioned dozens of pounds of steel shavings, perhaps worth reclaiming a few bucks on at his nearby recycler. Do they need to be turned into briquets first, with specialized tools like http://www.ars-inc.com/ ? Just curious if other builders (well, shavers) have tried this.
Last edited by domino11; Wed 13 August 2014 at 10:06.. |
#58
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Main beam end-plates welded
Today I cut the main beams to length, now that the rail grinding is done. I also beveled the ends, and welded on the end plates.
For a moment I thought about holding the plate in place with one hand while tack-welding with the other... and then decided that clamps were a better idea . |
#59
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Question - main beam angles?
I checked my main beams with two squares, to see if the top and bottom faces (as when they're on the MechMate) are coplanar. They're not .
If you look at the C channel on end, the points of the C are too close together. The angle appears to be about 3 degrees. I'm now at the stage of cutting and welding the legs, so this would be the time to fix it. I figure if I tweak the angle a bit where the beam meets the leg, then I can have the top face of both beams coplanar. This will help with the rail and rack alignment. The bottom face will be off a bit, but it won't matter that much. I'm welding the cross bearers for the spoilboard, so a gap of 2mm or 3mm will be easily bridged. Any thoughts or suggestions? |
#60
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Clever two-stage clampology!
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