Unimat 3 underpowered ?

[SiddleyParticipant @siddley]

I have just set up my Unimat 3 and I'm using it to do a few little jobs until I get the larger machines installed. Or at least I was…

I wasn't expecting it to have a great deal of power ( I had a Peatol once, so I thought I knew what to expect ) but when set up in a drilling configuration it was struggling to drill a 5mm hole in 3mm aluminium. My cheapo cordless drill has more torque. The drill bit I used was brand new and therefore sharp.

Are they all like that ? or could I have a motor fault ? – it's not noisy or rough running, it's just gutless.

[SiddleyParticipant @siddley]

[jason udallParticipant @jasonudall57142]

Well I wouldn’t expect it to struggle with 5 mm
Bearing in mind you turn say 25 mm
Belts slipping?
Pulley ratio?
Reverse?
New but cr*p drill?

[Keith LongParticipant @keithlong89920]

I'd certainly second checking the drill bit, I've had new cobalt drills that wouldn't drill butter – all needed re sharpening. Won't say where I got them as it could just have been a bad batch but it was a pretty big company that deals in all sorts of tools, screws, plumbing and electrical fittings etc.

Keith

[jason udallParticipant @jasonudall57142]

Had some gurrring supplied lefthand..tattoo correct..packaging correct .
Perfect drills just wrong handed.. ( made great screw extractors)..told to keep them on gurring..and correct drills sent foc..but they did want all batch codes to find out what happened..good company
Even followed up with what was cause…wrong part no. Called up on cnc grinder…and since ground fron solid and camera inspection file called up by part programme..no fault detected..part ident/packing called up by job card thus didn’t have same error…

[Ady1Participant @ady1]

To get decent torque the belts on a unimat sl needed to be pretty tight

The original rubbery belts were not very great for torque work

Polyurethane belting was great on an SL but there's also the pressure-wear on the bearings to consider if you take that route

You can find them on a well known site under "unimat belting"

[jason udallParticipant @jasonudall57142]

I think the op is talking unimat 3..
I leave my poly belts looseish ( 15 mm ping )
As you say saves bearing stress ( machine and me )
Allows for dig ins..teaches you that this is a light machine ( still machines 50 mm steel )

[SiddleyParticipant @siddley]

It's a Unimat 3. The belts are new old stock, I fitted them myself. I know there isn't any slip because the motor was stalling. I'm pretty sure if I'd been brutal enough I could have stalled it completely.

The drills however…hmmm…I didn't have much space to work in due to the shape of the casting I was drilling so I used a short series drill. Specifically one of a bunch of expensive CNC spotting drills I bought cheap from a workshop clearance several years ago. It's the first time I've used a drill from this batch. I'd better check them.

Thanks for the help so far…

[Ian PParticipant @ianp]

I know its very unlikely, but I had a similar experience to Jason with a quality (expensive!) 16mm HSS drill (reduced shank) which would not even open a 12mm hole drilled in soft aluminium!

Flute-wise it was a normal right hand bit, but ground as a left hand!

Because I was short of time I hand ground the drill, now though I wish I had made a stink with the supplier who's reputation now remains unblemished so learned nothing from my experience.

One other part I had replaced a long time ago by the manufacturer was Swagelok stainless 'Tee' pipe fitting with a seriously 'drunken' male taper thread on one leg. Considering the automated machinery that the fitting was produced on I am mystified how it was actually made, passing inspection was easy peasy by comparison.

[Geoff StevensonParticipant @geoffstevenson56049]

The Unimat range aren't any good for drilling anything over 1/4".. And that's doubtful. They look cute for the two dollar workshop but that's about all.. These things are only good for clock making, as long as accuracy isn't too much of a problem.. For model engineering.. don't waste your money..!!!

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

I had a Unimat 3 lathe for a long time since. The lathe has not high torque for heavy work. Suitable for fine mechanic work, watch maker or similiar and light work with smaller parts who is not possible in big lathe. Buy a larger lathe for heavy work and timesaving work with larger parts.

[JasonBModerator @jasonb]

I know in the past that I drilled larger than 6mm, seem to remember putting the 3-jaw chuck onto the mill head rather than the drill chuck that only goes upto 6mm capacity, probably did it in steps rather than straight in with a big drill. Also run it slower than the "correct" speed for that size drill in aluminium as you will get more torque as you gear the speed down.

As for being no good for model engineering, I did all the turning, milling and drilling on this bit of clockmaking using just the U3

[SiddleyParticipant @siddley]

I only have the Unimat because I won it for 50EU in an auction….
I think I'll probably sell it on…

[Graham Green 3Participant @grahamgreen3]

Siddley, have you had a look at just what horsepower these motors on a U3 are rated at ?

The U3 motor can get to be very sluggish, if somebody has decided to oil the sintered bronze bushes, with a 3 in 1 sewing machine oil – bad choice of lubrication that stuff.

This type of oil will dry out and clog up the sintered bronze bushes, then the bushes are acting like brake blocks, dragging and slowing everything down.

I bought a complete U 3 from the " evil-one " and the motor on it, was exactly as you have described, I carefully opened the motor and used a lot of paint thinners to dissolve this accumulated crud from the bushes.

Put it all back together and away it went, it will now hit the magic 4000 rpm again, it will NOT drill a 5mm hole thru 3mm ally in one go either, you have to sneek up on that size hole with the mighty midget.

Did a rather severe mod to another U3 motor and replaced the sintered bronze bushes with some BALL BEARINGS, wow, what an improvement, this ball bearing motor now has some balls about it .

This mod was printed in the Model Engineer many moons ago, think I even saw it on this site somewhere, it is/would be worth doing, if you want to keep the U3.

regards Graham

[Michael GilliganParticipant @michaelgilligan61133]

Siddley,

There's a useful summary page here

MichaelG.

[Julian Saunders 1Participant @juliansaunders1]

The Unimat 3 can be very accurate, I have made a 40.000mm quill to upgrade the vertical milling to tapered bearings, I have used it to make master patterns for Matchbox and Corgi, its accuracy was always great. I have upgraded the motors to a 0.5kw DC for main, and a 0.3KW 3 phase with controller on each motor, with reverse. Takes a 1" brass bar down to 0.5" in one pass, the Myford doth protest when I try it on that !!

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[SillyOldDufferModerator @sillyoldduffer]

Posted by 34046 on 23/01/2020 12:11:07:

Posted by Julian Saunders 1 on 22/01/2020 17:15:05:.

…

Heartily agree – absolutely nothing wrong with a U3 and well capable of more than clock making.

Jason's engine as above is proof of what it can do

Bill

Not so sure myself! Reading Michael's link and lathes.co.uk I find the motors varied between 40W and 125W. That's a very wide range, enough to make comparing one lathe with another dubious. Beware of chaps advising that their Unimats are wonderful: it's the state yours is in that matters and they ain't seen it cut metal!

My reading suggests a 90W 80% duty cycle Universal AC/DC motor was most common on these machines. (Some are only 60% duty cycle). That's plenty adequate for small delicate precision work, but clearly Unimat's aren't bruisers. Compared with the more suitable 450-650W DC or brushless motor fitted to a mini-lathe, Unimat motors are weaklings.

What a particular Unimat is capable of today will depend on the motor fitted and even more critically on what condition it's in. Over the last 3 or 4 decades, an underpowered Universal motor may have been thrashed, showered in 3-in-1, run on dud brushes or allowed to spark due to a failed suppressor capacitor. The commutator and bearings may be damaged. I wouldn't assume there's anything wrong with the lathe without having a critical look at the motor; maybe it's just filthy and needs some TLC. Unfortunately, if a Unimat motor is done for, replacing it doesn't seem to be cheap or easy. Not sure why – is it because they're a non-standard fitting? Lot's of old lathes accept new motors and a VFD without fuss.

Dave

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[JasonBModerator @jasonb]

I think Dave has got confused with the various Unimat SL versions which did have several different size motors unlike the Unimat 3 that only had the 95W motor and that worked well for me.

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[OldironParticipant @oldiron]

Posted by Ady1 on 10/10/2013 14:55:11:

You can find them on a well known site under "unimat belting"

WOULD THAT BE EBAY THEN ????????

[Author]

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