Design
Tradeoffs
When
CNC Router Parts and Fine Line Automation first published their 2' x 3'
router plans I spent a lot of time looking at them and analyzing them.
Part of that was to understand how it worked. That was the easy part,
particularly since I had already looked at a few other designs and
reviewed a few "build your own" books. The other reason I looked
closely at the design was to see If I could reduce my bottom line cost
for putting together the router.
There
were a number of changes that I made to the design in an effort to cut
costs. They were:
- Use
a cheaper version of the Acme Precision Feedscrews. McMasterCarr sells
1/2-10 5 start screws in 1018 carbon steel (99030A202) and 4140 heat
treated steel (98940A204) I would be using a Derlin Anti-Backlash nut
so wear on the feedscrew would not be an issue. I chose the cheaper
carbon steel feedscrews.
- I could manufacture some of my own parts.
This was not a given at the beginning. I had little or no experience
machining using the Sherline 2000. I purchased the linear slides and
the anti-backlash nuts from CNC Router Parts. I made my own bearing
blocks, NEMA23 motor mounts and Z axis mounting plate. I bought uncut
80/20 aluminum stock on eBay and CRS and aluminum from Speedy Metals.
- I made some changes in the design.
- I didn't buy any 80/20 1545 stock
for the uprights, using 1530 that I already had instead.
- I didn't use the
drill rod around the thrust bearings in the drive train. A discussion
on CNC Zone lead me to believe that the thrust bearings would not get
hung up on the feedscrews if I used the 5 start feedscrews.
- I
didn't use the "Low Profile" bearing
block on the Z axis. instead,I did add a
countersink recess for the bolt heads to just those two bearing blocks.
- I offset the gantry crossbar from the upright. It's an effort to put the spindle centerline closer to the gantry centerline.
This is the original CNC Routerparts Design. It requires a "low profile" bearing block to clear the Z axis mounting plate. | I raised the Z axis mounting plate by
putting spacers between the plate and the linear slides and under the AB Nut.. |