More About the #RobotTrapShop and Building Up a New Workspace

While writing my previous post about moving back South, I decided that there was enough content about putting together the garage workspace to warrant its own post. You see, this is really the first time I’ve ever really built up a workspace for myself only. I’ve built up and operated/managed quite a few facilities now, and even if it was “my shop” in the sense that I oversee and get to use it a lot, it still was always shared.

There was my time at MITERS, the MIT student makerspace – then upstairs in my research group the MIT International Design Center. Then another shared workspace at the old mill building we called “The Mochi Palace” prior to it being converted over for company use.  I suppose there was Big Chuck’s Auto Body over the spring and summer, but that was a very temporary and focused setup. My hope is this shop will be in place – or at least travel with me – for a few years yet.  But I’d be lying if I said that brief taste of having a workspace that was just mine and wasn’t critical to the operation of something else, or had to be kept up in appearances for somebody else’s tastes, didn’t influence my ultimate decision to seek less costly pastures.

First, before we get to the shop, though, we gotta talk about The Move:

I’d already containerized my life pretty well due to the somewhat frequent moving of shops in the past few years, so I just continued ordering more of the same sized 27″ totey-bins. The FIRST Robotics branded ones date back to the “Recycle Rush” game a few years ago and were picked up for real cheap. This meant that beyond loose large automotive tools such as the engine crane and errant van parts, the move was quite well coordinated. What I didn’t get into totes got put into some large cardboard boxes left over from company-received shipment (e.g. of toolboxes and big plastic tanks among other things).  The 16 foot Uhaul truck was filled to about 4 feet in front of the door, which was earmarked for furniture.  This whole thing was tied up in the “web of lies” formation shown above, as we nicknamed it.

While I’m not that big of a stickler for organization, it was a good time to take account of everything heavy that I owned, and I actually sold off a lot of stuff on eBay over the fall months that more or less funded the entire move! Hurray!

First order of business: Puke everything inside the garage and deal with it later!


Couple days in and I’m working on setting the shelves back up, at least, so I can start throwing totes and robot parts onto them.

I also decided to just spend a weekend in early January and build myself some workbenches. I spent a while scouting Craigslist, classified ads, and equipment dealers, but wasn’t really finding any ones that looked good in the quantity I was hoping for. There were some, but I’d basically be buying new anyway costwise (Then I’d just buy new). So instead of dropping like $1000 on workbenches when I can blow on Overhaul instead, I decided to spend $100 at Home Depot and knock these out. I made two 3 x 8 foot benches in the “usual” hobbyist style – for some reason, basically every workbench I’ve seen be handmade is made this way. Guess it’s a pretty solid design for the effort involved.

I also made a rolling table for Overhaul and eventually other projects, just the same method but with the legs cut short so I could put it on a set of total-locking casters, and have it be…

…equal in height to the benches for easy transfer of things on and off!

Overall I was quite satisfied with the “Majority of 1 Saturday” work and cost. My only regret? Using the OSB as a top. I might skin it in hardboard or MDF later on. The tops are double layered 1/2″ OSB – nice and sturdy, but don’t run your hand across it. I coated the edges with some left over spray-on urethane I brought down, which lowered the splinter factor somewhat.


By mid-January, it’s almost looking like a functional workspace! I noticed there was a light fixture with a broken bulb up above the lower set of rafters, so I decided to get a gigantic 100W (actual!) LED “corn cob” light to put up there. It really lights the place up, but casts strange shadows due to the rafters.

I ordered extra shelves to unpack Big Chuck’s Auto Body and also finally give my screw collection a home.


When the opportunity presented, I also went on tool runs based on findings from Craigslist, Facebook Marketplace, and the like. I managed to land this ‘vintage’ Craftsman bandsaw for only $100. I was out to get a vertical bandsaw to at least be able to cut most sheet materials to make stuff if need be, and wanted to avoid getting a chintzy small one. This Craftsman was the perfect size – I could wrestle it around, but also trusted it was solid enough to do actual work.


One cheeky change I made though, right after getting it, was re-gearing the saw through its belt drive. It was definitely a wood-cutting bandsaw by intent – there’s only like a 2:1 ratio between the motor and the blade wheels. I changed this to a roughly 4.25:1, halving the blade speed. Once I put a 14 tooth variable-pitch bimetal blade on it, this thing was basically unstoppable in aluminum. I tested cutting a 2″ wide bar through its width (i.e. a 2″ depth of cut) and it was handled admirably. Just can’t do steel on it, since the blade speed is still much too high- I’d have to put a back gear on it or something to be able to cut steels.

In early February now, and I’ve basically set the space up for Overhaul work. You can see another Craigslist acquisiton to the left – the 3-ton size arbor press. I haven’t given it a permanent home yet, but it just gets clamped to whatever bench I need to smash something on.

Rewinding a bit back to the week of move-in… one of the first things to go up is the 3D printing station and Equals Zero shipping area.

Later on, I found this table on the damn sidewalk while driving home one day through the back residential streets. How quaint! Good thing I only have vehicles that can convey large volumes of stuff. I gave the top a quick sanding and oil coat, and here we are – supplemental shipping/assembly bench or electronics area.

Check out the row of Equals Zero stock shelves in the background. I found a “local minima” price solution that was ordering a certain Home Depot shelf size online (picking up in person) and then ordering a certain set of casters on Amazon. There’s more of these now, actually.

Speaking of which, I also handed Jeff Bezos some money to dress out this corner as an EE station. Hopefully I’ll pick up more instrumentation too, relatively soon! Right now it’s enough to put together Ragebridges and whatnot, which is all I need it for.

Obviously these facilities will evolve as I need them. For now, they’ll carry me through most of the projects I think I’ll get up to, and allow some basic consulting work to happen too. There’s the unfinished basement which is currently very underutilized because it’s not climate controlled and tends to be a bit moist and drafty – not a good environment for 3D printers or electronics. I currently have it just as cold storage, but might move more things there such as the van parts shelf if I end up collecting more tools.  But here we are! Welcome to the #RobotTrapShop.

Reassembling a Bridgeport J-head with Uncle Charles! And More About Hooking Up Your Annoyingly Chinese VFD

You know what? I’m tired of having sweet-ass machinery sitting around not hooked up. Last time in “Charles takes forever to set up his own shop because he’s sick of setting up shops”, I did some battle with a generic Chinese VFD and completed what the damn factory couldn’t be buggered to by adding the dynamic braking components.

Though Bridget ( <3 ) ran since then, there were some issues. The spindle brake was so worn it was difficult to change tools, and the head made the “Bridgeport Clack” from the high/low speed dog clutch being worn. The motor’s V-belt was also severely worn. I wanted to tear it down for a rebuild of sorts, so I spent a little while watching “How to rebuild a Bridgeport head” videos. I decided that all of these videos sucked, and that I was really only interested in repairing the brake and replacing the timing belt and V-belts.

So here is my documented take on how to take apart a Bridgeport 1J head. In it, I discover that it wasn’t as terrifying as I had thought originally, and that old-school American engineers might commit some abominations but damn they’re good abominations. I guess this is kind of a Beyond Unboxing, too.

Step 1: Dismount the motor, which is retained by two studs, one with a set of two jam-nuts to let it move a little for belt tensioning, and another that’s the ball handle (you unscrew the ball handle and then untighten what it’s attached to). Then, crank the head about the Y axis (roll) 90 degrees.

Six socket head cap screws live underneath the belt cover casting and retain it to the steel back-gear housing. You can take all these off; pins retain the belt cover afterwards, and it needs to be yanked off. Don’t worry, it’s not heavy. But there’s one catch:

The back-gear timing belt pulleys both have flanges. To remove the belt cover means taking off one of the pulleys with it, and that means removing the belt with it. You have to remove the four slotted head screws that keep the pulley flange on. Once it’s gone, the belt slides off with everything, like this:

This setup is quite the abomination. The timing belt has no tensioner – it relies on good will and good spacing. Mine was getting a little loose from the years. While I haven’t run the machine hard in back-gear range to see if the belt skips, I ordered a new belt anyway since it’s a “Might as well” item. The belts, and other rebuild components which will be seen, came from H &W Machinery Repair.

While the cover was off, I cleaned off the thick layer of congealed rubber dust and spindle oil. I didn’t break into the back gear cavity, however – if you do, remove the nut on the big pulley and use a gear puller or Three-Phase Prybar to pop it off, then undo the remaining screws. Some times the gear cavity is filled with grunge; if your machine had multiple owners, chances are it has both grease and oil in it.

I loosened the cover and a lot of remnant oil started pouring out, so I’ll likely keep it together but drown it through the front oil port later.

The second step pulley and back gear timing pulley live with the belt cover and has a large bearing carrier assembly under it. To undo this, I need to remove the shifter mechanism.

The pins that ride in the shifter groove also help retain it completely. Problem: One of them was completely stripped and wobbly. Due to the pressure exerted by loading springs underneath the pulley, I couldn’t get the pin to bite on its remaining threads and back out. So I drilled straight down the center and threaded the hole for a #4-40 screw that I could then grab with pliers and pull on:

The stock machine has slotted head pins; H&W sells a replacement with a hex wrench drive. Here’s the victim screw driven in…

And a few tugs later, the shifter ring is freed.

The pulley then flies off the other side, since there are loading springs underneath it.

And here we have the brake assembly. The brake is simply a phenolic drum brake setup that crams against the interior of the pulley. Nothing sophisticated at all!

To remove the brake, you have to remove the 3 slotted-head shoulder screws holding it down. However, to do that, beforehand you have to undo the three hex nuts on the top side (underside in these photos) – they prevent the shoulder screws from loosening.  After that, the brake can be wiggled off gently. It will snap closed, due to its own return springs, so watch your fingertips .

The small tongue on the upper right of the bearing bore is the cam that toggles the brake shoes.

Many times, when a Bridgeport spindle brake is worn, it means two things – one, that the brake shoes are worn down, but what I found is that the cam had also dug a little trench into the brake shoes where it makes contact. So this has reduced the effective travel length and caused the brake shoe to lose engagement. In fact, it seems like the harder you wail on the brake lever, the quicker you induce this 2nd failure mode.

Also, Brigeport brake shoes are expensive. Speciality exotic part, sure, but I can do all 4 brakes on Mikuvan for less money using nice ceramic pads too! So I wasn’t going to replace these, but simply make the cam bigger.

Returning to the top side, the brake cam escapes if you untighten the set screw holding its handle pin in place. The pin slides out and the whole thing falls apart.  The cam and shaft assembly are on the upper right.

The fix? Make the cam bigger by welding repeatedly over it, building up more metal, then sanding and filing it down! This was after the rough-sanding stage. I filed a gentle round onto the engaging edges so it doesn’t cause further erosion of the phenolic laminate brake shoes.

Alright, we’re now on the reassembly path. The brake cam is going in back in…

Secured up top, along with installed brake shoes and re-tightened locking nuts.

I reassembled the shifter ring after cleaning the whole area and thoroughly greasing it. In Bridgeport maintenance, you’re supposed to oil the shifter ring daily in production use. I think I’m fine with putting in a few greasewads where it needs to be instead of having to clean up even more crusty oil grunge down the line.

The belt cover is remounted now.

Before final assembly, make sure to thread the timing belt and V-belt back onto the pulleys. Then as you line the belt cover on, wiggle the timing belt onto its large pulley.

When finished, you can then replace the small screws and pulley flange.

Putting this motor on was the precarious part, since it involved holding something pretty heavy and wiggling it from an awkward angle! I threaded the two jam nuts onto one side in order to hold it in place for….

Final head tilt. Here are the newly installed parts! And there we  have it. Shifts great, runs smoothly. Still makes The Bridgeport Clack, but further research showed me that is all in the quill spline drive and there is not really a way to R&R that short of replacement. I’m fine with it.

Moving onto controls! I can’t use this thing from a potentiometer dangling by its wires forever. You may, but I have standards.

I put a little money on eBay into some more machine style switches and buttons.

I had two buttons left over from a project long ago, so they were going to be used as the Run and Stop functions. The same potentiometers got transplanted into a panel mount which I screwed into the housings. Knobs were a matching pair (rare! legendary!) found at MITERS.  The two-position switch will control forward vs. reverse.

The wiring was concocted using disembodied Ethernet cord, which is one of my favorites for pirating cables from their intended purposes. The VFD’s Use of Manual™ just showed a bunch of normal looking switch symbols connected to the forward/reverse, start/stop/reset, etc. inputs.

This is where I discovered another great undocumented feature of Use Of Manuals. The diagram was a lie, but only enough to get you in trouble.

I had problems with it accepting my switch configuration. I found that the VFD didn’t want to read my stop button at all, and it accepted any flip of the direction switch as a “run” command. That is, I can toggle the forward-reverse switch for it to change directions, but it wouldn’t take my stop button input. I’d have to hit the STOP button on the control panel of the VFD. After that, I couldn’t start it by using the start button, but just changing the state of the direction switch would let me turn the knob and increase speed again. Well, all of my settings seemed to be correct for the job, so I was a little confused and figured there must be Undocumented Behavior. This was certainly inconvenient to use the damn thing intuitively, and I certainly wouldn’t let anyone else touch it in this condition.

It took a few friends with experience in industrial controls to point out what I was doing wrong.


That is a diagram for a normal industrial magnetic contactor, showing how Start and Stop buttons are typically wired. In these things, the STOP switch is always closed unless something causes it to open (either by accident or on purpose). The Start switch, on the other hand, briefly powers the contactor coil which pulls in not only the main contacts, but a little auxiliary contact that keeps the coil energized and hence the contactor latched. You can see how any number of interlocks (e-stop systems, overload detection, etc.) can work its way into the STOP circuit and turn the machine off when needed.

The VFD is technically designed to replace this setup, so it’s expecting the Stop button to be normally closed. Well, all my switches are N/O type (close when pressed). So the VFD was waking up in an unexpected mode, I guess, where it seems to default to treating any forward/reverse switch inputs as “Okay, start running”. Well this seems a little scary of a failure mode.

Anyways, the Use Of Manual shows all switches as N/O, so it definitely assumes you already know industrial control practices to use it. That’s another endearing characteristic of Chinesium… you better know exactly what you’re searching for, or else you might find it.

Well that’s quick fix. I didn’t order modular contacts with my switches, but luckily they’re manufactured modularly enough to use the same set of contacts, just internally turned upside-down, to become N/C. Now my control panel works as expected – the stop button puts the VFD into slow-down-and-brake, then start will ramp the motor back up to the previous speed it was at. In run mode, I can change speeds at will, including braking down to zero speed manually.

And here’s the test video.

Now that I understand this setup (or do I….), I can build the second control box accordingly. It’s also easy now to add an anti-face-eating emergency stop mushroom button anywhere in line!

The next machine to go online will be Bridget’s cute Japanese friend, Taki-chan!

how about no