What's Going on at the Grant Street Garage?

 I just checked, and my last blog post was over 3 months ago! Blame Covid-19... November and December are always busy for a church musician, but add in the necessity to prepare everything to be online instead of in-person, and the time demands quadrupled. But there's one bit of that that I'm really proud of, and I invite you to check out our Christmas Eve Lessons and Carols service at this link:

https://youtu.be/EI_ZcFDfdW0

The other reason I haven't posted is that when I was in the shop, I was working on a project that was time-consuming, but that I judged not very interesting to see step-by-step. I've been building a Little Free Library - a neat idea that allows people to share books for free. A patron had contacted the Make717 makerspace looking for a woodworker to build it, and I decided to say yes. I built it to last for decades, from marine grade plywood, and carefully glued and caulked every joint. It's pretty big for a Little Free Library - 36 inches wide. The patron paid my materials expenses, and gave a very nice donation to Make717.

There's a matching base also. It just left the shop today, picked up by another craftsman who will add a metal roof. After that, it will go to an artist from the Pennsylvania College of Art and Design, who will decorate it. It will eventually be installed at the Fulton Elementary School here in Lancaster.

The other big news at Grant Street is that after years of wishing, I finally have a real lift! It's a MaxJax lift, designed for spaces with low ceilings. The MaxJax company was acquired by automotive lift giant BendPak last year, and they made numerous design changes to improve the MaxJax. I'm happy to have the latest version. A lot of do-it-yourselfers install these themselves, but I spent the extra money to buy it from a BendPak dealer (Automotive Lift Service in Hanover, PA) and had them evaluate my concrete and install the lift for me. After watching two experienced techs take six hours to install it, it felt like money well spent.

Santa brought that fancy-pants creeper underneath Beck TD - it can be set at several different angles, and it makes working underneath the car a very comfortable affair. 

This week, I've been playing with a little project concerning my Sherline milling machine. I bought it used, and have never been happy with it. Part of the problem was the wobbly, low-density fiberboard base that the prior owner made. In addition to being unstable, there was no easy way to use a dial indicator or dial test indicator to ensure accuracy. My magnetic base for the test indicators wouldn't adhere to the aluminum base of the Sherline, and of course the wood was useless too.

Last week, I literally woke up from a dream where I envisioned a solution. I used one-inch-square steel stock to make front and rear "outriggers" to function as a base. I cut the angled ends on my metal-cutting band saw, and welded in nuts for the feet. The mill is attached to the legs by socket-head cap screws in threaded holes.

The digital read out (DRO) on this mill was an annoyance too, because it was on top of the mill head. It was difficult to read, especially when the head was low. I got tired of stooping to try to read it, so I welded up a DRO stand, attached to the rear leg.

After priming and painting and taking some care in routing the cables, I had a very nice setup. 

I first tested the bare table in the X-direction, and was very pleased that runout was almost unmeasurable. Even better, testing the threaded aluminum "tooling plate" that I had made months ago found a similar result - it was out less than half a thousandth of an inch over its length. Also in the picture above is a vise I made, mounted to the tooling plate, and we'll talk about that in a minute.

This photo shows how easy it is to test accuracy now - the magnetic base sticks firmly to the steel legs, and the indicator easily reaches parts to be measured. Unfortunately, having that ability told me bad news too. The vise I made, which I was very proud of, is not accurate enough for precision work. The problem is that the moveable jaw lifts an unacceptable amount, making precision cuts impossible. It's good enough for lots of things, especially precision location for drilling of holes, but not for milling.

That's not all the bad news, either. The setup in that last photo allowed me to test the Sherline vise that came with the machine. Those has a claimed accuracy that is out of this world, but this one has clearly been tweaked during its life. I measured it several ways using this setup, and on a granite surface plate, and it's out of whack around a thousandth of an inch per inch of X-axis travel. Not much, but not good enough for machinist work.

I started this Sherline project because I was frustrated with my inability to do really accurate work. Now that I have a good, stable base, I was able to see where it's good and where it's bad. Now I'm in the market for a small, super-accurate vise!