UNIMATS ARE NEAT BUT???

[skogkatt007]

The unit I had turned a taper of .001" per inch.

Let's not forget the Unimat PC. Said by Tony Griffith to be the best model they made. But the bearings are clamped/welded in place. There doesn't seem to be any way to change them.

 

[Smithdoor]

They are far more portable, and potentially more accurate than a 7" mini-lathe.

They were originally marketed as a combination hobby tool, in addition to the mill / drill press option which you do run across quite frequently, at one time they sold accessories to turn them into a little jigsaw, table saw, and grinder. Other than the milling column, these other accessories are not common and can be expensive.

Unimats are not much bigger than a watchmakers lathe, and a more accurate watch makers spindle was even an accessory offered for them. It is probably not unfair to consider them a budget watch or clock makers lathe.

They are neat, I have no need for one, but I do want one. Lack of need keeps me patient waiting for one to turn up nearby and cheap enough to overwhelm my better judgement.

It as accurate as the machinist is.
You do need to check the out before making a part. Only the lathe most 3 jaw chuck are within 0.002" so you be use 4 jaw chuck.

Dave

 

[Pylonracer]

It as accurate as the machinist is.

Even an accurate machinist will struggle with a machine with inaccurate lead screws and twisted headstocks.

I have found my Unimat 3 to be very accurate and also turns very round at around 0.002mm out of round at the 13 to 15mm range.

They are nice machines but so are Sherlines.

 

[Pylonracer]

Let's not forget the Unimat PC. Said by Tony Griffith to be the best model they made. But the bearings are clamped/welded in place. There doesn't seem to be any way to change them.

Yes I remember reading that, but I struggle to see how a bar bed lathe will be better than a cast bed like on the Unimat 3. I did not know about the bearing fitment in the Unimat PC but that is another downgrade mark IMO.

 

[skogkatt007]

Those bars may not be the detrimemt you suspect. Consider the type.of work you're doing. Years ago I participated in the Multimachine discussions. First the goal.was to make a machine out of an old engine block. Then the design was changed using bar ways and concrete. This was done during 1 of the wars where machines were difficult to source or whatever the reason was.

 

[Smithdoor]

Even an accurate machinist will struggle with a machine with inaccurate lead screws and twisted headstocks.

I have found my Unimat 3 to be very accurate and also turns very round at around 0.002mm out of round at the 13 to 15mm range.

They are nice machines but so are Sherlines.

That is 0.000,078"
Most modern lathes only 0.000,1"
I have own a Tool makers lathe {Mori Seike} the was under 0.0.000,05" .
How close do you want.

Dave

FYI
It would be hard to find someone that owns the equipment to measure that close too.

 

[Smithdoor]

Even an accurate machinist will struggle with a machine with inaccurate lead screws and twisted headstocks.

I have found my Unimat 3 to be very accurate and also turns very round at around 0.002mm out of round at the 13 to 15mm range.

They are nice machines but so are Sherlines.

FYI
Most work only needs to be a TIR of 0.00,5" [. 012mm] . Some may need 0.000,2 [0.005mm].

Dave

 

[skogkatt007]

The issue of interference fits enters into the discussion. I read somewhere once that a headstock bore needs to be .0001" less then the bearing diameter. Don't know if that's true. An old "hand" once said you can always polish to within tolerance. But to readily achieve a bore that's .0001" undersize, you're going to needle a spindle that has a tir of less then .0002" or better. And some polishing. Does that make any sense?

 

[Ulma Doctor]

What kinda NASA contracts do you have? Accuracy past .0005” is pointless to chase unless you’re sending something to orbit.

 

[Pylonracer]

What kinda NASA contracts do you have? Accuracy past .0005” is pointless to chase unless you’re sending something to orbit.

A lot of model engines need accuracies better than 0.0005" in certain areas.

I mentioned 0.002mm which is right about a tenth of a thou but that was out of round of finished components.

Having said that I could turn down to tenth of a thou on a Unimat 3, cant the top slide around at about one degree off the spindle axis and wind your cut on with that angled top slide, also needs super sharp tools, diamond tools are best.

This photo is of a piston in an EMCO Compact 5, you can see that the yop slide is angled over by 1 degree. Works well.