Mini Mill 3 Axis DRO

A while ago I got hold of this Shumatech DRO 350 kit to fit to my Sieg SX2 Mini Mill. 

The mill is great for doing semi accurate stuff to layout lines and simple handwheel count jobs, but if you want to do things much more accurately much quicker a digital read out is the way to go. This kit creates a display and control unit that takes inputs from digital vernier calipers that you install onto each axis of the machine. The 350 does all sort of special features such as electronic edge finding and compensation for tool diameter and loads of things I don't even know about yet so it should  make me and the mill much more capable.

The kit comes as a printed PCB (the one shown in a previous post), all components (including a pre-programmed PIC chip), connectors for interfacing the calipers to the board and a nice enclosure that has to be milled to suit the PCB buttons and display segments. This is then covered with a silk screened overlay.

I live and work about 150 miles away from my workshop so only really make it there on weekends, so this project was to be built at home after work.  

First thing was to knock up a static safe workspace to try and avoid wrecking the IC's.

A ground lead for the static mat was made up using some flex and a 1 megaohm resistor.

Then starts the very long process of placing and soldering components as per the diagrams and legends on the board. This took place over quite a few evenings just getting an hour or two when I could.

With most of the required basic components installed and the right voltages in the right places I could then install the first row of IC's that drive the first row of 7 segment displays and the PIC chip with the 'program'.

Terrible photo (as most of them are) but I was quite happy to see the first banner line show up, meaning that I managed to not destroy anything with static or heat so far!

Knowing that the first line was good I then moved on to installing the second line of IC's and display segments, and got the second line I was hoping for. (It only displays the software version, the other two display blocks do work!)

I ran out of small diameter solder at this point so seeing as I was on a roll I went down to Maplins to get some more and get some air as the room was getting a bit hazy from all the solder smoke!

After getting the solder the third row got seen to and ended with desired results.

 With all the display related systems working I then moved on to installing the interface circuits for the scales.
Again more soldering of components and jumpers, everything looks alright but I need to get the calipers to actually test this part to see if it works.

Next step was to install the buttons, so yet more placing and soldering

 Last components to be installed were the status/indicator LEDs above the top display line.  With these done that's it for the actual PCB assembly, everything that I can test without the scales seems to work! Happy days.

Below is a short video of some button pressing

Next things to do now are to machine the enclosure suit the board and install all the ports and connectors on the back. I need to measure up the mill and design the attachments before I know what size scales I am going to get so will have to hold off on final testing till then, but it should be 'reeet.

Taa

Pete

Z20LET Engine Build: Part One

Being around Shell's car a lot has made me want a Z20LET,

A good ad came up on ebay which I quickly jumped on, then went to the workshop the next weekend to find this...

Pretty much a complete engines worth of parts, but minus 2 pistons (broken in storage?), flywheel and the turbo/exhaust manifold.  Also got a full GSi engine loom, full VXR engine loom and a VXR charging loom so have pretty much all the connectors i'll need when I come to make the new looms, but that is a way away yet.

All I've done with the head so far is remove the camshafts so I can more comfortably leave it inhibited till I come round to rebuild it, the same job we did on the head in the Corsa in the last post but without all the teardown and not as much cleaning! It all looks good on first looks except a bit of corrosion on 2 or 3 of the hydraulic lifters but at around £6 a shot for new ones I wont lose sleep over it

To start things off while I had some time I felt to make some constructive moves other than cleaning and inspecting the haul so set about freshening up the block.

A second Z20LET in the foreground with the balancer shaft assembly removed. Bit of a lemon this one, could be salvageable but will have to spend some time on it first.

Water pump and timing sprocket removed

Oil pump removed

With the ancillaries off it was then time to get the crank out and see what the main bearings were saying,

Some tool improvisation was necessary to get the main bearing caps off, they were pretty well seated!

With the crank out the main bearings could be inspected, I was very happy to see that they were in mint condition, so were the main and rod journals on the crank

Very happy with the crank journals (those bands are meant to be there)

The block had already been re-honed ready for new rings

With the block stripped the very long road to decent paint started

The definitive degreasing weapon, you could probably kill someone with the dense steam-like jet of hardcore solvent that comes out of this

I did more wire brushing that day then most other people have ever done it their life.... The kettle got used and a bag of Jaffa Cakes disappeared after this.

It was then finally time for paint, after the first coat it looked like this

The next day while the paint hardened I went after some more quick progress with the upper and lower sump parts

The block then had another going over

With the bits painted I had to just see where this is going, so just stacked them up, there are a few spots on the lower machined face of the block that need paint but ill mask this and sort that out next time

With a bit of a start made with the painting the first component for inspection/overhaul was the oil pump,

Note the impact driver wasn't going to be used anywhere near this! I was just using one of the bits

 

The oil filter mounting boss was a PITA to get off, the flats are below the rim of the casting and the thread on the back is quite a large diameter, a tool had to be made or I was going to end up wrecking this expensive part,

Note the shallow tacks on the top were to reduce warping and keep the critical dimension after the proper bead on the inner face, a nut was then buzzed on

 I had to bolt the oil pump onto the spare block to get enough power into it with the breaker bar still!

After stripping down the pump then got the wire brush treatment (more delicately though!) and a bit of deburring inside

 Only bad thing was one of the bolts for the timing cover had been sheared off by the previous owner, not surprising though as they are shouldered bolts with a zero rad undercut. So just drilled and extracted it.

All the internal parts cleaned and checked and the casting got painted but forgot to get any pics of it. That's as far as things got that session, as I spent over an hour just inhibiting all the parts for storage as I probs wont be in the workshop for another couple of weeks   : (

I need to get some main shells, both crank oil seals, big end bearings and then decide which out of my two sets of conrods im going to use, before I can start building the bottom end back up. I may try and shift the rods Ive got and get a full compliment of LEH (VXR) rods and pistons as they are coming up occasionally on Ebay for reasonable money, but Ill let my terrible impulse buying habit sort that out for me.

Taa