Monday, May 28, 2018

Easy Cinder Block Benches

The subject of my latest instructable:

https://www.instructables.com/id/Easy-Outdoor-Cinder-Block-Benches
We recently had our 1200 sq ft back yard paved as a patio because it was just growing weeds and not being used.  We are very happy with the result and have started adding patio furniture.  The first addition was this pair of benches made of 4x4 posts and cinder blocks.

Thursday, April 26, 2018

Box Joints on the Radial Arm Saw

The base of my CNC router was made with box joints on the Radial Arm Saw. I cut one end of all the boards at the same time using a 1/2 inch dado stack with the saw rotated as shown:

After cutting each slot, I cranked up the arm by 1/2 inch. 
 After cutting one end of all the pieces, I flipped them over to repeat on the other end. Assembled, the frame looked like this:

I've been using this frame for about 3 years, rolling around on casters and shaking the Dickens out of it without any issues.

Monday, February 19, 2018

Thursday, February 15, 2018

After a few tweaks, the DIY CNC is back online!


In the past few weeks I've been working on a new CNC instructable, but I was having trouble getting my motor drivers to cooperate. At first I couldn't seem to get them all to even start up. I decided to try out these Texas Instruments DRV8825-based Stepper Motor Driver Module designed as a drop-in replacement of my existing drivers:

I was getting better results but still missing some steps so I checked the 3.3V from my modified phone charger. It was showing the expected voltage on the multimeter, but when I looked with my $20 single-channel oscilloscope, I saw frequent peaks above 9V.
I added an electrolytic capacitor I found and smoothed out the peaks to around 3.6V. That's it, right? Wrong! It took a few more trial runs and a night to sleep on it to realize I also had a mechanical binding issue on the x-axis. After removing 2 screws, it's working great again.