Assembly Starts

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I still have a few design details to work out, but I’ve gotten anxious to see some metal take shape. I started with cutting all of my aluminum extrusions to length. I installed my new blade on my miter saw and checked to see that it was square in both directions. The built-in clamp was too wide to properly hold the 20×20 extrusion so I used some quick clamps instead. This was an 8 ft long piece so I supported the far end with the table from my Woodmaster Multi Tool (the original Shopsmith).
I noticed after a few cuts that the ends weren’t getting cut quite as clean. I took a look at the saw blade and picked off a few aluminum chips that had gotten stuck. Then I used some wax lubricant on each tooth and also put a bit along the cut line of the extrusion. For each subsequent cut I just lubricated the extrusion. Things seemed to go very cleanly after that.

I checked the ends with a square and they seemed fine, but I would later find out that they weren’t quite good enough for one location. The length came out very close; within half a mm.

All the extrusions, ready to go:

 I was getting ready to tap one of the MakerSlide extrusions for the X-Axis when I accidentally pulled my clamp apart too far and pieces went flying so I had to take a quick detour to figure out how to get it back together. This was NOT how it went together:

Finally I think I got it back in order:

I clamped the end of that quick clamp in a vise and then clamped the MakerSlide and a scrap piece of 20×40 extrusion in the quick clamp so I could tap the end. Here I’m using another small piece of extrusion with one hole drilled out for clearance for an M5 to help keep my tap square.

I also decided to put a transfer pin through the other hole to keep my tapping guide in place while I worked.

After the holes were tapped I bolted the carriage plates to the end of the X-Axis and checked them for perpendicularity. This is the only spot where I really needed to be concerned with being square because this will determine how square my X axis is to my Y axis. Unfortunately it wasn’t very square:
It’s cold out and I didn’t really feel like getting my mill ready to clean up the end so I decided to shim the extrusion with some aluminum foil. Six layers did the trick here and brought my extrusion square with the carriage plate.

Next I needed to adjust the length of some spacers I bought. McMaster didn’t happen to have a 13.35mm spacer so I had to make due with a 14mm one. (This is what happens when you mix English and metric parts.) I tried using a bit of sandpaper on my bench and rubbing the spacer on that, but I couldn’t keep it perpendicular. Next I tried resting the spacer in the slot of some scrap extrusion and using my disk sander and a miter gauge. This worked pretty well except on the second spacer when I over-achieved and had to use a shim washer to make up for the extra mm I took off. I used my thumb to press the extrusion to the miter gauge and my forefinger to slide the spacer into the sanding disk.

Using my spacers and lots of other hardware in my fancy parts bin shown in my last post, I started assembling the X-Axis assembly.

The lower wheel axle is quite a pain to get together because it has two eccentric spacers which protrude into the aluminum plate. Therefore you need to leave the top screws loose a bit so you can open up the bottom of the plates. I have a feeling this will be a pain to adjust later too.

Next I started laying out my bottom frame pieces. I used an old mirror I had to act as a flat build surface. I added some extra T-nuts into the extrusion before I tightened the ends. It’s easier to ignore them later than to unbolt everything to add some.

I did the same with the top frame. Here I had to use some vise parallels to keep the V rails of the MakerSlide extrusions off the flat surface.

Before I tightened the left end of the frame down, I made some measurements to make sure my Y-Axis MakerSlide rails were parallel. I noticed that once I locked down three corners, the forth had a bit of spring to it and didn’t want to rest closed. I flexed it into place though and I don’t think it will cause me trouble.

Next it was time to add the legs. The design calls for the lower frame to rest half an inch above the floor so that a wooden milling surface can be placed underneath. I neglected to build my wooden plate first to space the lower frame, so I had to make due with some half inch aluminum jig plate instead. I also added some L-Brackets loosely near the top in preparation for the upper frame.

To rest the upper frame in place before I tightened everything down I used some quick clamps on each leg. Then I measured and tightened each corner down.

Finally I added the X-Axis assembly. I had to remove the lower wheels and then replace them after I rested the assembly on the upper frame’s Y-Axis rails. So far it’s looking just like how I designed it. The Y-Axis movement is very smooth. My goal is to finish the X and Y movement and get my electronics in place before I start fabrication of some of the trickier Z-Axis parts.

Lessons Learned

  1. This assembly will definitely need some adjustment screws for leveling the top frame to the build floor. I should be able to incorporate something without much trouble though.
  2. My miter saw did not cut square enough after a basic setup. It would benefit from a proper zero-clearance fence and floor insert. I knew about these things, but I didn’t have the right material to make one and was lazy.
  3. Surface mounted angle brackets would have been better for the top and bottom frame assemblies. (The ones that would sit on the top or bottom of the frame rather than on the front or side.) This would eliminate the need for an elaborate flat surface with vise parallels in assembly.
  4. A little wax lubricant helps quite a lot for cutting aluminum with a miter saw.
  5. Aluminum foil is a handy shim stock.