Monday, January 24, 2011

Some Progress and Some Planning

Well, I pretty much completed the mechanical construction this weekend. I installed the Y-axis bars and the chassis. I had to remove and rebuild all the bearings on the chassis in order to get them to slide smoothly on the bars but I managed it eventually. Only the installation of the bed remains and I may wait until the heater arrives and make an aluminum bed instead of the laser cut acrylic that I have now.

I discovered one more problem with the mechanicals that I will have to fix. The idler bearings for the belts don't have quite enough room for my 1/4" belts. The belts stay on but they rub against the fender washers and the friction will be a problem during operation. I will have to remove all of them and add another washer or two to make a bit more room for the belt. Not difficult, just one more small tuning type task.

I also ordered a new z-axis belt from SDP-SI. I was able to order the same belt that I had before but with an extra two inches of length (39" vs 37").

Next up - the Electronics!

The next step is the installation of the electronics. I have the Gen-3 remix from Techzone and the boards are considerably smaller than the original boards for which the laser cut mounting boards were designed. I discovered a great alternate design on the Techzone Gen-3 Installation Wiki page that mounts on the side of the Mendel and supports all the boards on a single panel:

Single board electronics mount.

Side mounting of the board with zip ties.

This one is made out of a used nylon cutting board but I think that I can find a scrap of something around the garage to use.

Note - there are actually two Wiki pages for installing the Techzone electronics. The one with this nice mount is largely incomplete. I think that they abandoned it and started over. The one that contains the most current and complete information on installation can be found here.

On the Wiki they also discuss the possibility of using an additional stepper driver board for the extruder rather than using the extruder board to drive it. Apparently it results in a more reliable and quiet extruder. I will have to look into this. Perhaps I can find some information on the forums from someone who has tried it.

I admit to being intimidated by the prospect of installing the boards and wiring everything up. When doing the mechanical build I was able to disassemble and fix anything that I messed up. With circuits I may not know until I turn on the power that I have an issue and it may be too late at that point to avoid the smoke and sparks. I will just have to proceed carefully and do any testing with only the minimum number of boards connected in order to limit any damage that might occur. In a worst case I can always buy replacement boards from Techzone but I would like to avoid spending too much more on the machine.

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