The 'Unimat' 4

The new, old lathe arrived yesterday. The Unimat 4 is manufactured in the far east, and you can certainly tell the difference. A proper Unimat it aint.
I carefully checked it over last night and it is in good condition for what it is, and will make a good lathe in the end ..... but .... there were a number of problems.
I stripped the entire machine down, and the beds and ways are in good condition with no knocks or scrapes. There are signs of hand lapping or scraping and the ways are well finished. There was swarf and shit everywhere and signs of the original packing grease. This was all removed. It took ages to get all the crud out of the leadscrew though.
The machining of some of the parts is passable at best and not good at worse. What was indescribably stupid were the aftermarket products. A quick change toolpost (QCTP) and a taper-turning top slide. The toolpost had been fitted upside down with a huge washer on the top. At first I couldn't fathom out why, but it then became obvious. The securing bolt that fits the clamp nut was at least 5mm too long for this model. Instead of cutting it back down (as I have now done) the previous owner had driven it into the bed of the cross slide which had deformed it! He had then flipped it over and added the washer to take up the difference. I have checked and this is the bolt supplied with the part. Stupid of the manufacturers.
The taper-turning slide had similar problems. The locating shoulder was about a millimeter to long to fit the hole and the securing bolt was also about 3mm too long. Again I think the previous owner had tried to force it to fit, which is sort of understandable if the product is sold as ready for the machine. I had to grind the shoulder down so that it was a drop in fit and reduce the length of the securing bolt.
Both aftermarket products now fit correctly and the QCTP is really nicely made and will come in very useful.

The deformed part of the cross slide was riding on the un-machined part of the saddle. Useless for any kind of meaningful work. Eventually I will hunt down a replacement, but for now I had to grind back a relief which has left a small hole in the base of the slide. Luckily not anywhere that matters but it may left swarf into the thread. Damn.
All the gibs had to be reset, mostly I fear due to the damage to the slide, but it now runs cleanly and all the threads are clear. The tailstock appears to be fine, so i just gave it a clean up. The keyless chuck as supplied is useless really, it's so long that it reduces the between centre size to about 5 inches. These machines were originally supplied with a 10mm Jacobs chuck, which is missing.
Here's the lathe as it arrived:



Now to the more serious shortcomings of the machine. The motor mount is bloody awful! On the old SL/DB it was a rough, but sturdy alloy casting machined for the location points. This model has a piece of 3mm pressed steel to carry the motor and the idler and it bolts to the back of the headstock. It flexes like crazy. there's a point between the headstock and the motor where you can flex the mounting plate. You can move the back of the motor by 3 or 4mm. Not good.

On a first test cut it was obvious that there are runout problems. About 20thou at 2 inches from the chuck. I have ordered a dial gauge to find out if it's the chuck (hopefully) or a problem with the headstock. I am beginning to wonder if a tool was driven into the original Jacobs chuck and that's why it's missing.
If it's the headstock, then I either have to fit new bearings (a daunting task) or find another headstock. If it's the chuck then getting another won't be a problem.
It could be that the thread of the chuck is as bad as all the other bits so I've ordered a tap so I can run it through.

If I had access to bigger machinery I would try to machine a new motor mounting plate from quality alloy. Anyway I had to adjust all the pulleys since they didn't line up and I've ordered a new set of belts too.

Why go to all this trouble? Well the machine was CHEAP even for this model and it has much better bed clearance than the SL. Even with riser blocks.
If I spend another £100.00 getting it all working then it will still be cheaper than a second SL or a Mk3.

My micro workshop

 

My plan is coming to fruition! I managed to order the milling post for the old Unimat from the USA. Even with shipping it was 25% cheaper than I can get one here in the UK. Madness.
I bought an old (vintage) Grayson model engineers pillar drill for a song. It will almost certainly need a bit of work to get it back into shape, but I'm in no rush.
The second Unimat proved to be a real problem, but I found a Mk4 for a good price. These have a slightly underrated reputation being a far eastern (not Austrian) manufactured unit, but it's a late model and should be good for my sort of work. Also many more accessories are readily available for the Mk3 and Mk4, as opposed to the SL-1000 where parts come up infrequently.

With the compressor I already have, a small engineers vice and possibly a small bench bandsaw, I will have all the equipment for my micro workshop. I will then start looking to add all the accessories to the two lathes. One advantage of this is that the SL milling head only needs a support block to work over the Mk4 table, so a lot more work can be done.

I await delivery of all three machine parts, pictures will then follow.

I've done more work on the M114, and I now have 10 cast wheels waiting for machining. I'll use them as a test of the new Mk4 when it arrives and report back. Meanwhile here are the images for the work I've done.


Six disks make up each rear idler.


Drilled and cut ready for assembly


The two rear idlers ready for paint.


Selection of 'likely' candidates from scrap to make the pattern match for the road wheels.


The final parts selction for the pattern match.


Assembly work started.


Hub nearly complete, it will need some Milliput to finish


Assembly work completed now for the Milliput ....


The completed pattern match, now they will be cast in resin and machined.


A completed test wheel, this one was rejected since the casting has lost some edge detail on the left. It will be used for test fitting and ground clearance.

Scratchbuilt M114 APC

I decided to try and buy a second Unimat to use as a drill / milling machine. Didn't quite go according to plan. I sold some old radio gear on ebay that I haven't used for a couple of years. I managed to raise £250.00 for my new machine tool. At the time there were 4 Unimat SL lathes on ebay, all a bit more than I wanted to spend, so I hunted around and found one on Homeworkshop for the right price. I emailed the guy and he said it was still available, so I asked him to mail over his paypal account details so I could pay him........ heard nothing for two days. Mailed him back only to be told that it had been sold! To$$er!
By that time all the ones on ebay had gone, bugga. So I've put a couple more things on ebay to raise a few more quid while I wait for another one to come up.

In the meantime the drawings from George Bradford in Canada arrived. Fantastic! Along with a load of images and reference material I have enough to start work on 5 vehicles.
I chose to begin with an M114 APC since I had tried to build one 20 years ago from an article in Millitary Modeller, but was defeated by the wheels and tracks. I have more time, a little more experience and some better tools now.
The M114 is easy and very difficult all at once. The main chassis is all straight edges and no compound curves or difficult angles. However, the wheels and tracks seem to e unique to this vehicle and therefore very fiddly and tedious. We'll see how I get on over the coming months eh?

Here the main side panels have been cut from Plasticard using the 'score and snap' method, George's excellent drawing can be seen on the left. His is for an M114A1, but I will be building the straight M114. The differences are minor.
As an aside, Blogspot's image uploader needs revision, it won't put images at the insertion point! It keeps putting them at the top of the blog which is a pain, unless I'm doing something stupid?


I've added the base of the chassis and the front and rear panels. A couple of bracing pieces have been included to keep everything square.


The simple main body of the chassis completed. I decided not to cut out the hatches and have to build an interior. Mostly because I didn't want the hassle knowing what was to come with the wheels and tracks.


I've started to add surface details here, the hatch covers, fuel filler caps, lifting hooks and vent grills. All from bits of plasticard or cast resin. A first template for the wheels can be seen on the right but I don't know if I will use it or not yet.


Another view of the first detail stage. The 'Mayflower' in the background is awaiting rigging and sails to complete. Another really fiddly job that I'm putting off for a bit.


Finally a couple of images of the current state of play. There are a few more details to add to the main chassis before it's complete and I start on the wheels and tracks.