Monday, October 17, 2011

Lathe

Things have been going very slowly around here for the last few months! Work, other projects and a back injury followed by a foot injury have conspired against me!

Despite being busy, I have managed to do a small amount of work on the Spitfire. The windscreen is now out and didn't reveal too many horrors - just a little rust in the rain channels! The bonnet is now stripped down completely apart from the rear bonnet cone panels. I want to keep these on for as long as possible to get the right shape but I really need to sort out the bit where they meet the bonnet wing flange. There are three panels spot welded together here and rot has, rather unsurprisingly, taken hold. I think the easiest solution is going to be to chop it out and let some new metal into the flange before tackling the cone panel and then the wing.


Once I have repaired all the panels, I need to start getting them cleaned up and I've made a bit of an investment in a 3hp compressor from Jawel Paints so that I can get some grit blasting done. Grit blasting has a bit of a bad reputation with classic car restorers and a quick read of the Internet might have you believe you were practically guaranteed rippled panels. The reality of it is, though, that damage to panels like that can only be caused by industrial equipment and is not something that can easily be achieved at home!

To complete the kit, I bought a cheap sandblasting gun from Machine Mart which may or may not be any good (I haven't tried it yet!) and some J-Blast Supafine grit which came highly recommended on the MIG welding forum.

One of the other projects I have just finished is this mini lathe. I bought it off eBay as a complete wreck. It's an Emco Unimat design made by Elliott Machine in the UK. There is a huge following for these little lathes and parts crop up fairly regularly on eBay. According to http://www.lathes.co.uk/unimat/ my lathe is a Mk4 Unimat and probably originated from around 1959 - 1960.


I started the restoration off by stripping the paint. I couldn't decide if this was original or not but I guessed not because it looked like green Hammerite and it was literally slapped all over everything (including the plastic motor brush caps) but I have since seen a few finished like this! Either way, it got a few coats of the same grey POR15 I used to repaint my gearbox.


The rusty metalwork got a thorough dunking in derusting solution, whilst the seized chuck got a thorough soaking in penetrating oil followed by a bashing against the soft wood of my workbench!


The trickiest bit by far was the motor. Unimats are powered by a U-90 motor made in Holland by Motoren Eindhoven. Its a nicely made motor and has big 'Oilite' bearings but suffers from a low duty cycle. For every 8 minutes it's in use you have to let it rest for 2! It did work when I got it, but I took it apart anyway to repaint and instantly realised that all was not well with it. For a start, there was some very dodgy soldered connections inside that had been left bare and, secondly, there was supposed to be a suppressor inside. The only trace it had ever been there was a couple of soldered tags!

This was a bit of a problem. The motor would run without the suppressor but the brushes would wear rapidly. Unfortunately, the original type of suppressor hasn't been available for years and the only one available is too large to go inside the motor. I decided that the only real option was to use a suppressor from Maplins and mount it outside the motor.

Fitting the suppressor and putting on a new flex involved a lot of fiddly soldering in a very dingy, confined space but I eventually got it done! I find a soldering gun rather than a soldering iron makes these unpleasant jobs much more straightforward, not least because mine has a light on the front that comes on when the trigger is pulled!


The last job was to fit a new switch and plug. The originals were Bakelite and had seen much better days!

That's it! After a few false starts (due to a brush not making contact) the motor ran up nicely and sounded much healthier than it did before. All that's left to do on it is to heatshrink the suppressor to the cable to tidy it up and think of some things to make on it. My drill press has some nasty plastic bits on the feed handle that could be replaced by something nicer so I think that might be my first project.

2 comments:

WoodCraft said...

Hi there

Nice job on the lathe i did the same project the other day on a mk4, the paint could have been the original and had a hammered effect.

Again very nicely done.

Regards
Otto

Anonymous said...

Nice job on the Unimat. The hammered finish was original but so what. I just purchased the same model off Ebay and I'm probably going to paint it Safety Yellow. It is hard to match the original colors so I ask, "Why worry?" They came in various shades of hammered finish from silver grey, greenish grey and a greenish blue silver. At the time the Unimats were made good quality hammered paint was available in all colors imaginable. Now the color choices for hammered paint are very limited and none of the ones I have seen match and they're no where near as durable. Your's and mine are the very sought after last models made of cast iron. All accessories fit these models. The later models were cast in aluminum and Zamak (Pot Metal) and do to metal creep from heat expansion they are not as accurate. I have three Unimats, two aluminum and one cast iron. I'm taking the cast iron one to my grave and you should too!