Since it looks like Tom's Tool Store has gone the way of many of our old suppliers. I used the Way Back Machine Internet search engine and located his old site. I was then able to download his old online catalog so I have the information and photos for the Unimats.?
I did the same thing for the old Unimat Parts, both of these old sites are full of great photos and information. You can go to these sites and save each page and create a folder to keep this information.
It looks like Blue Ridge Machnery also no longer has any Unimat parts.
Jeff
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Unimat 4 motor now working again.
First post after lurking for a while here in the UK so be gentle with me.
My Unimat 4 stopped working a few weeks ago, when the start button was pressed the fuse in the plug would blow, tried a few times and could sense the 'pop' was in the motor casing, sounded like a flashover, checked out the motor all looked okay, tried the motor on a twelve volt battery charger and the motor turned over nicely so nothing wrong with the motor..... Cleaned all the carbon dust out of the motor, refitted it and tried again and this time the 'pop' was in the plastic control box on the top of the motor. A track on the circuit board had blown right through so I repaired the track with a short piece of wire and disconnected the wires for the motor at the terminals, pop, the fuse went again. On the circuit board I checked out the rectifier (the black component about 20mm square with four legs) which the burnt out track led to and it showed a dead short on the meter (probably as a result of the flashover) so a new one was fitted and I was now getting power at the motor terminals - 220v DC (mains supply is 240 AC). Then I thought, but the motor on this machine was 24v DC max so something wasn't right. The next component down the line was a three legged transistor thing called a 'Triac', about 10mm square with a metal tag on top, checked the code number and ordered one for about 2 pounds GBP, this came today and was fitted in minutes. Hey Presto one working lathe again.
So apparently these Triac things do go without any warning and show no sign of damage. I guess the original 'pop' was the 220v flashing over from a brush holder to the motor casing and blowing the fuse.
Now I'm not an electrician but an engineer who can trace faults in machinery and I would advise caution when working on mains powered machines, if you don't understand electricity ask someone who does.
The lathe is probably from about 1995, the motor is the original fitment and is silver in colour, used couple of times a week for light jobs and is pretty accurate for turning masters for casting model railway components.
Hope this post helps people and remember, be careful with electricity.
Dave.
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Re: U3 carriage ¡®yawing¡¯
Sometimes the speed does affect the amount of deflection.? If you run certain metals like stainless and some steel alloys at very high speeds, you can overheat and in effect heat treat them making them glass hard.? That hardness change can destroy the edge of a high speed tool.? Also harder material = stronger material = more deflection.
If you run certain carbide insert tools with a shallow depth of cut and at very high speeds you can rub and overheat and work harden the metal that way as well.
If you are using high speed tools with these small lathes, keeping the edges razor sharp reduces the cutting forces that are transferred from the rotating part to the tool.? This reduces deflection.
If you keep the cutting edges well lubricated that makes them cut more effectively and reduces cutting forces and material welding on the cutting edge.
If you choose to use insert tooling like DCMT inserts it is best to use the aluminum finishing inserts with a sharp edge on all materials.? This reduces cutting forces.
Rigidity = good machine finish.? If you can deflect the cutter with your finger, it is time to try and take out any backlash in all the axes.
Does the amount of tool bit deflection change due to the speed of the spindle?
Does the hardness of the metal you are working? with change this?
For my final finish cut, I frequently just push my tool bit holder to take that final .001 + off of the diameter.
Probably not the most precise method of machining but it works.
Tamra
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Re: U3 carriage ¡®yawing¡¯
Does the amount of tool bit deflection change due to the speed of the spindle?
Does the hardness of the metal you are working? with change this?
For my final finish cut, I frequently just push my tool bit holder to take that final .001 + off of the diameter.
Probably not the most precise method of machining but it works.
Tamra
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Re: U3 carriage ¡®yawing¡¯
Need to consider the effects of tool geometry.
1) stiffness...when traversing "forward" the tool deflects backward and results in a shortening of length. The dynamic change of direction from forward to reverse relieves the tool bending and then digs in on the reverse stroke, taking a little bit more off.
2) cutting tool geometry...most hand ground tools are "handed" with back rake not only leaned back but also angled away from the predominant direction of cut.? Hence right and left tools.? Reverse cuts result in negative tool geometry, and can screw up the finish.
3) exceptions...radiused blade tools with straight back rake, but even those will dig in on the withdrawal, due to lateral floppiness.
4) I was always taught to rough in both directions and final roughing done in the preferred direction of the tool.? Then measure with a micrometer and the final few thousanths in the same direction.? For critical parts, even roughing in one direction only.
5) In turning, that little bit of a cut on the reverse is the equivalent of a spring pass.? Best to do that in the same direction.
6) Btw doming or cupping on cross feed is not unusual,? It is usually due to the changing feed rate as you move toward center.? The surface speed of the cut changes as the diameter changes assuming constant RPM.? I have found that taking several very light passes at a higher RPM helps to neutralize the over-feeding as you head towards center.? The cutting tool is progressively taking heavier cuts as you head toward center.? If you take light final cuts at a higher rate of speed then progressively really slow down the feed as you get to? center, you can usually take out a lot of the cupping.? Cutting tools exhibit this effect regularly because they are so floppy in the lateral direction.
I recall the tool taking a fine cut on returning from facing off quite often on various lathes. I think it depends on the metal being cut and the way the tool is ground. I've never worried about it. On the Unimat I'd expect it if I'd taken a deep cut quickly, which could cause some deflection of the toolpost. I do most of my work with hard brass (CZ121) or free cutting alloy (2011) and haven't noticed this happening, although, thinking about it, the things I've worked on recently have not involved much facing off. I also keep the slideways nipped up at all times. I'd like to find a way to lock the carriage without needing to reach for a hex key every time. Less worried about the cross slide since that has a dovetail that can be adjusted to be just right.
I do recall facing off a 250 mm diameter piece of cast iron on a big lathe one day, to make a small surface plate. When I checked the flatness with a straight edge I found it was down 1 mm in the centre. I'd finished up with a shallow cone. Nothing on the lathe suggested this could be corrected by some sort of adjustment. Maybe it had been like that since the day it was built. So I don't expect perfection from any of these machines. If you get high accuracy that's a bonus.
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Re: U3 carriage ¡®yawing¡¯
I recall the tool taking a fine cut on returning from facing off quite often on various lathes. I think it depends on the metal being cut and the way the tool is ground. I've never worried about it. On the Unimat I'd expect it if I'd taken a deep cut quickly, which could cause some deflection of the toolpost. I do most of my work with hard brass (CZ121) or free cutting alloy (2011) and haven't noticed this happening, although, thinking about it, the things I've worked on recently have not involved much facing off. I also keep the slideways nipped up at all times. I'd like to find a way to lock the carriage without needing to reach for a hex key every time. Less worried about the cross slide since that has a dovetail that can be adjusted to be just right.
I do recall facing off a 250 mm diameter piece of cast iron on a big lathe one day, to make a small surface plate. When I checked the flatness with a straight edge I found it was down 1 mm in the centre. I'd finished up with a shallow cone. Nothing on the lathe suggested this could be corrected by some sort of adjustment. Maybe it had been like that since the day it was built. So I don't expect perfection from any of these machines. If you get high accuracy that's a bonus.
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Re: U3 carriage ¡®yawing¡¯
Thanks both. Maybe I am doing something fundamentally wrong. If I make a cut traversing along towards the headstock, surely the lathe shouldn¡¯t be cutting more material (even a fraction) when reversing back in the other direction (towards the tailstock)? Am I meant to back out of the work at the end of a cut and then reverse (in which case all sorts of issues of backlash and accuracy come into play)? Sorry, I am such a novice!
Talking about the ¡®the force is down¡¯ - I have wondered about this recently - should boring actually be carried out on the ¡®far side¡¯ of the internal face? This would seem to be the direct equivalent of turning on the outside face.
I¡¯m thinking now of trying the keep plates in more of a gib arrangement, it¡¯s non-destructive anyway.
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Re: That Dang Wooden Box¡
Don,
Thank , you! I will check that out.
Dick
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http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
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Re: That Dang Wooden Box¡
A Craftsman maybe?? I just did a Google search for "soft start Craftsman router" and got several hits.? Might be a place to start.
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Re: U3 carriage ¡®yawing¡¯
I could have written this, but I wanted to double check the "big
lathes" in the garage. I believe that one can just grab the apron
and lift - not far, but noticeably.
Another in general: It helps to be aware of forces in general and
what opposes them. In this case the force is down in normal
turning. Does anybody do much "upside down" turning on the back
side of the spindle on Unimats? I know some people swear by
parting off that way on the big lathes.
On 8/23/23 04:14, Keith S. Angus wrote:
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I have always assumed the purpose of the Keep Plates is to stop
the carriage falling off, not to hold it down to the bed. In
normal use the carriage is held down by the cutting forces. Most
larger lathes I've come across work like this. If you have
problems with slack in the system when facing off, tighten the
clamp on the carriage. That's what its for. In general, any axis
that is not moving when making a cut should be locked.
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Re: U3 carriage ¡®yawing¡¯
I have always assumed the purpose of the Keep Plates is to stop the carriage falling off, not to hold it down to the bed. In normal use the carriage is held down by the cutting forces. Most larger lathes I've come across work like this. If you have problems with slack in the system when facing off, tighten the clamp on the carriage. That's what its for. In general, any axis that is not moving when making a cut should be locked.
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Re: That Dang Wooden Box¡
As long as we are discussing box joints I have a question about router tables. I used to have a small router table that had an aluminum table and four steel legs. The router was a soft start and I think it was very similar to the small DeWaltIt was very handy. I no longer have it but would sure like to find one but I don¡¯t know what to search for.?Can anyone here identify what it might have been so I could try to find one. Thanks
On Tuesday, August 22, 2023, 11:34 AM, txlonghorn1989 via groups.io <txlonghorn1989@...> wrote: On Sat, Aug 19, 2023 at 02:52 PM, Pachyderm wrote:
I have had bad luck cutting clean box joints in plywood.
Hi Wade.? I have a Delta table saw and a nice Freud dado set that I use to make boxes with box joints.? I assume tearout is the issue with your box joints.? If you're cutting these on a table saw the issue might be that your saw blade (or router bit if using a router and table) may need sharpening.? It will also help if you have a fresh backing board behind the joints as the saw blade/router bit exits the joint.? I found a free Unimat on CL last year which came without a box but I plan to make one and like you try to recreate the original box as much as possible.? Although, I sure like the box that Phil built. Good luck! Mike
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http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
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Re: That Dang Wooden Box¡
A free Unimat on CL?? Wow!? That kind of find is almost unheard of!
-Dave
On Tuesday, August 22, 2023 at 09:34:48 AM PDT, txlonghorn1989 via groups.io <txlonghorn1989@...> wrote:
On Sat, Aug 19, 2023 at 02:52 PM, Pachyderm wrote:
I have had bad luck cutting clean box joints in plywood.
Hi Wade.? I have a Delta table saw and a nice Freud dado set that I use to make boxes with box joints.? I assume tearout is the issue with your box joints.? If you're cutting these on a table saw the issue might be that your saw blade (or router bit if using a router and table) may need sharpening.? It will also help if you have a fresh backing board behind the joints as the saw blade/router bit exits the joint.? I found a free Unimat on CL last year which came without a box but I plan to make one and like you try to recreate the original box as much as possible.? Although, I sure like the box that Phil built. Good luck! Mike
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Re: U3 carriage ¡®yawing¡¯
Thanks Chuck for the reply.
There is enough room for 6mm of keep plate and the heads of the socket screws, so I suppose it would be possible to have two 3mm plates and grub screws with locking nuts to apply pressure as per the slide gibs¡
The other idea I had was to mill a very shallow rebate in the new keep plates (as you did, leaving the portion that makes contact with the bed) and then shim them back up with feeler gauge material until the fit is good. Metric feeler gauges have a useful range going from 0.05 mm (I¡¯ve just ordered four!).
It did strike me (while I was lying in bed of course) that the other thing that could cause this was if the bed was bent, slightly arched - the middle of the carriage would be pressed down on the bed but there could be a gap (and thus play) at the outer edges. So I¡¯m assessing the beds of my two U3s. One (in bits already) is flat but ever so slightly twisted according to my surface plate. I can just get the 0.05 mm feeler gauge under the corner. I don¡¯t think that¡¯s enough to cause an issue.?The other U3 is being dismantled.
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Re: That Dang Wooden Box¡
On Sat, Aug 19, 2023 at 02:52 PM, Pachyderm wrote:
I have had bad luck cutting clean box joints in plywood.
Hi Wade.? I have a Delta table saw and a nice Freud dado set that I use to make boxes with box joints.? I assume tearout is the issue with your box joints.? If you're cutting these on a table saw the issue might be that your saw blade (or router bit if using a router and table) may need sharpening.? It will also help if you have a fresh backing board behind the joints as the saw blade/router bit exits the joint.? I found a free Unimat on CL last year which came without a box but I plan to make one and like you try to recreate the original box as much as possible.? Although, I sure like the box that Phil built. Good luck! Mike
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Thank you,John! The Unimat SL is very capable. I occasionally?use mine for a small repeat production job made from 4140. Amazing little machines!
On Monday, August 21, 2023, 8:29 PM, OldToolmaker via groups.io <old_toolmaker@...> wrote: Hello John,
That is some very nice workmanship on you tap followers. What lathe did you use to machine these tools? Just curious.
Dick
--
http://www.homemadetools.net/ forum/?OFF- SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI- LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
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Too cool! I need to make something like that, too.
Bill in OKC?
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
Expect in one hand, expectorate in the other. See which one gets full first.
On Monday, August 21, 2023 at 07:50:24 PM CDT, John Entwistle via groups.io <jentwistle3@...> wrote:
I¡¯ve completed my first ever SL project - a pair of tap followers that fit into the tailstock. 
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Hi Dick I did them on my Unimat SL.?
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Show quoted text
On Aug 21, 2023, at 9:29 PM, OldToolmaker via groups.io <old_toolmaker@...> wrote: ?Hello John,
That is some very nice workmanship on you tap followers. What lathe did you use to machine these tools? Just curious.
Dick
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
|
Hello John,
That is some very nice workmanship on you tap followers. What lathe did you use to machine these tools? Just curious.
Dick
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
|
I¡¯ve completed my first ever SL project - a pair of tap followers that fit into the tailstock. 
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Tool247
Tamra
OldToolmaker
Bill in OKC too
John Entwistle