spindle bearings

Spindle bearings. Every machine with a rotating cutter (such as a CNC router) has them. While they are not nearly as impressive from a technology standpoint as something like a microprocessor or an FPGA, one still has to stand in awe of the manufacturing process used to make these things. The steel has to be utterly, totally pure, and the surfaces are ground to a mirror finish, and to a roundness of a few microns. After doing this, the manufacturer then picks through them, looking for pairs that are exactly that same couple of microns off, and matches them up in pairs. Here’s a picture of the ones I just installed:

bearings 001-enhanced

Because they were old stock in a scruffy looking box I was able to buy them on ebay for slightly under $200. If you bought new stock in shiny pretty boxes they would set you back about $350. They are the hardest working bearing on the machine. When they are in top condition miracles are possible, kind of like a prima-donna ballerina or a tenor in Italian opera.

bearings 002-enhanced

As you can see from the picture above, they live in a bad neighborhood. The red circle is around the “bit” (it slightly resembles a drill bit) which gets shoved through the material at speeds up to 10 inches per second while spinning at 15,000 rpm. My finger is pointing to the housing where the bearings live. Hour after hour, day after day, year after year that spinning bit rudely transmits vibrations, sideways loads, and belches out clouds of chips and dust, a microscopic fraction of which finds it’s way into the bearings despite the best efforts to keep it out.

As these miraculous bearings go into decline, however, they are the exact opposite of an operatic singer. They make more and more noise. Everybody who owns a CNC router lives in dread of a dying spindle. You cope. You slow down the speeds a little, and look for those particular speeds where the resonance works in your favor and try to do your cutting at those speeds. But you can only cope for so long, and eventually you just have to bite the bullet.

You can either pay in time or money to get them installed. Hiring the job done costs an amount in the low four figures, so I opted to run the gauntlet of finding the exactly right $30 an ounce grease, building the special tools necessary, and learning how to carefully run the new bearings in while monitoring temperature. A plastic bag can become a temporary clean room.

Now I get to enjoy the quiet “whir” of my new bearings! It’s a beautiful sound.



The Jiggernaut was a project I recently completed for local design think-tank Mixed Media Engineering. They first came to my attention when I read a story about the 2011 Red Bull Creation Contest, or “buildathon”, or whatever it’s called. They competed as “1.2 Jigawatts”, and built this thing:

It’s sort of a big hamster wheel that receives text messages and prints them out on the pavement while somebody is walking inside it. It stole the show and won first prize. Needless to say, when I found out these guys were from Minneapolis I had to look them up, congratulate them on their win.

Then last spring I noticed they had an interesting Kickstarter project going called the  Jiggernaut, a bicycle frame building tool which looks like this:

They needed 100 sets of parts, so I ordered up a unit of “door grade” 3/4″ MDF. Door grade is a premium quality MDF which is stronger, cuts cleaner, and causes less wear on the tools used to cut it. A unit is a big stack (in this case 35 sheets) which looks like this:

Since Each Jiggernaut requires 26 parts, those sheets of MDF quickly turned into a lot of pieces:

And a lot of dust and chips. The six bags in the above photo represent 2 days of cutting. It’s great to have a serious industrial grade dust collector!

The tall guy on the right with “torit & day” in white letters is my hero on jobs like this.

This was a fun job. It’s great to think about all those folks who contributed to the project on Kickstarter brazing up their own custom bike frames!

I cut the letters, Sean did the rest

Forgot to take pictures of these sign letters while they were being cut, but here they are assembled to the steel backing. The material was 3/4″ Extira, a variety of MDF (medium density fiberboard) with outstanding weather resistance, which is also used for exterior architectural trim and moldings.

The picture above shows the twin of the sign in the first picture in place and mounted to the building. The design, assembly, and mounting were done by the very capable Sean Doyle.  He also cut the delicate tree design on the corner of the building, which is visible above his left shoulder by hand with an oxyacetylene torch. The rest of us can only dream  of having such well developed fine motor skills.

stuff like this happens when you fill out the “contact” form…

Here are some parts I made for another arcade game related project:

I believe this project involves adding an arcade style joystick and buttons to a PS3. These are 2 sets of parts. Some of these parts required a groove in their edge to accept a plastic “T” molding. The following picture shows a part before grooving on the left, a part after grooving on the right, and the special vacuum fixture in the middle. The vacuum pulls any warpage out of the parts, making sure the slot is perfectly centered all the way around.

On Monday he filled out my contact form and we exchanged some emails discussing details, Monday evening he stopped by with the material (5/8″ MDO plywood), and now (Thursday afternoon) he has precision cut parts ready to assemble. How cool is that?

mounting a small display

Here’s a job I did recently for someone building their own arcade style game unit. He had a cute little USB driven display that he wanted to use for stuff like game selection and to reset the main unit in case the software developed indigestion from an improperly handled exception or an interrupt gone wrong. This was the end result:

Here’s a pic of one of the standoffs I made to attach the mounting ears of the display to the front plate:

The gray stuff it’s embedded in is some scrap acrylic I used for a test cut. The next picture shows the back of the aluminum plate.

Since the standoffs were to be epoxied to the plate I made the base big for extra glue contact. I also made him a router template that he used to precisely cut the plywood parts. He sent me DXF’s output from Adobe Illustrator, which seems to be a favorite among game modders.

fun with HDPE

Interesting little parts made from HDPE. I probably shouldn’t tell what they’re for yet. This started out as a DXF file from an ancient version of Adobe Illustrator which was emailed and imported just fine.

A quick wave of the heat gets rid of a lot of the scuffing and scratching on the original surface of the sheet, much like flame polishing acrylic. The rounded over edges are easily done on the CNC router.

I wound up running these in 12″ by 24″ sheets that yielded 48 parts per sheet.

deep foam

Prototype foam parts. About 5 inches deep at the lowest point. Coffee cup shows scale. This is a test cut made in cheap one-pound foam from the lumberyard. The yellow lines are where the two-inch sheets were glued up with urethane foam.

Here it is flipped over after cutting the bottom side.

And here is the finished part, cut free from the frame.