Base be done

Karl now has a completed machine base. Lets walk through the steps that have been done so far. 

The machine bed was bolted and leveled using music wire from corner to corner to keep the frame on a single plane. There is always going to be some warp, but we did our best to keep it at a minimum. 

Once the base was leveled against the frame, the machine bed welding began. All of the joints were welded and then the cross members were dropped into place and also welded. 

The next step was to add in some extra material to give the tapped holes for the linear rails more metal to grab onto. 

Karl needs to be able to move with some level of accuracy. Steel directly out of the mill isn't exactly flat or straight, so the next step was to cut down the tops of the welded straps using the 3 plate lapping method. This was only to get things close(ish), so when the epoxy is poured it will have a better chance of coming out correctly. 



The 3 plate method requires that you take 3 different surfaces and lap them together. We used one of the 3x6 tubes for the gantry, stuck some adhesive backed sandpaper to it and started cutting into the rails. Once things were cut down, the process was to place the sandpaper onto the rail that was just cut and use it to cut down the 3x6 tube in a rotating manner.

First the 3x6 cut the left rail surface, then the left rail surface was used to cut the 3x6, next the right rail was used to cut the 3x6, and then the 3x6 was used to cut the right rail. This went on for a week or so until the rails were in decent shape with flatness and what not.

The reason this step is important is because to use the mag drill to make the mounting holes, we needed something that was in decent shape so the holes could be drilled and tapped for the linear rails. 

After our backs were broken from the 3 plate method, we poured on some epoxy to get things quite a lot closer in terms of flatness. 

After the epoxy was set, we scraped it until the surfaces for Karl's linear rails were decent enough to mount things down. The linear rails were set, straightened and bolted down. The next step was to build mounting brackets for the gantry to set on and to get something to get our ball screws in place. 

 

Now that both linear rails were set and the ball screws were attached, we could finish off the gantry support beams. These are built from 1/2 plate steel, 3x6 tubing and 2in flat steel. 



The final step in getting the base done was to mount the motors. We are using teknic Clearpath motors on Karl for now. Specifically the  CPM-SDSK-3446D-ELS model was used for the X, and Y axis. To find this specific model, we called Teknic and they are crazy helpful in determining which motor to buy. 
https://www.teknic.com/ 

That's all for now. We are about 45 days into this build and still have the Y and Z axis to complete and also all of the electronics to bring Karl to life. 

Base be done
Donny Davis 13 January, 2021
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