TECH TIPS PAGE
Practical, information for maintenance and operation of the Unimat DB/SL.
If you have technical advise you would like to share , let me know and I'll post it here...
DB/SL SPINDLE SPEED CHART
* UNIMAT TECH TIPS PAGE *
Please have a look at these other pages of interest on my Unimat web site
Special attention should be paid to spindle bearing maintenance. As this is the key to accurate spindle run-out! Before you put your DB/Sl into service after purchase or storage, service the bearings. Keep in mind some of these units are 45 years old and grease hardens up. If your spindle bearing are noisy or worn and can not maintain run-out .0005" , replace them! I have purchased a stock of exact spindle replacement bearings For bearings, see my belts & accessories page
Maintenance section Unimat Manual
The spindle bearings are grease packed. To service, the spindle should be disassembled and the bearings regreased. To do this remove the spindle cartridge from the headstock and unscrew the nut retaing the step-pulley, holding the shaft and turning the nut counterclock-wise. If the nut is difficult to remove, apply penetrating oil. After slipping off the pulley, gently drive the spindle shaft out of the bearings from the rear, using a wooden mallet to avoid damaging the shaft's threads. Laying the parts out in order same side down as you remove them simplifies reassembling them later. Wash the parts one by one in solvent, wipe them clean with a lint-free rag, and regrease the ball bearings with a general purpose bearing grease. Since the bearings' brass ball retainers hold the balls rather loosely, be careful not to lose balls that might fall out.
The spindle cartridge is assembled much like a bicycle wheel hub. When reassembling it be sure to replace the dished washers, which preload the bearings slightly, in correct order. With the spindle assembled, tighten the pulley retaining nut all axial play is taken care of with proper preload washers. The spindle must spin freely in its bearings to run smoothly at high speed.
Bearings run in old dried grease, improper grease or no grease. Will become noisy! Once noisy no amount of lubrication can change this.
Here is a TECH TIP from:
Shane Hallsworth
Regina, Saskatchewan
Canada
I have a unimat (hammer green). Besides doing regular headstock maintenance I would also recommend that the tailstock be dismantled, cleaned and given a very light coat of grease. I also dismantle my 3 and 4 jaw chucks and clean any chips or dirt that may wedge in the threads.Without this maintenance your chucks will not close accurately and could wear out a lot faster.
TECH TIP:
Unimat Model # 736.21410. This is the Unimat made by Emco, and private labled for sale by Sears Roebuck & Co, ( Sears part # ). It is the same as any Unimat DB200 ( just different tag).. You can use all of the belts, accessories & Manual for the Unimat DB/SL models. See my belts & accessories page.
TECH TIP:
Spindle Bearing Installation Instructions:
Here is a copy of my spindle bearing instructions. This should help you in proper reassembly.
Preload Washers:
Something of interest from the manufactures specs.: When installed between two ball bearings, they assure perfect positioning of the bearings with no side play. They provide precise bearing preload and proper tension, extending the life of the bearing and eilmiating excessive noise.
Here is a TECH TIP from:
Eugene Saboda
Heres a little tip, maybe you know it already, when using the feed handle to move the spindle in the head stock, in the vertical position it's works OK, but in the horizontal position it has a clunky feeling to the feed handle. By dropping a small ball bearing ( about 1/4" ) in the feed handle hole first and then replacing the handle it will smooth out and give one a fine feed and feel to the handle.
DB/SL PULLEY SIZE INFORMATION
Here is the pulley size information I have gathered over the years, of selling replacement belts.
Measurements are outside diameters
U.S. DISTRIBUTED DB/SL
Motor Pulley: 18 - 30 - 42 mm
Intermediate Pulley: 18 - 30 - 42 mm
Spindle Pulley: 65 - 75 - 85 mm
EUROPEAN DISTRIBUTED UNIMAT ( they did not necessarly use the DB/SL tag, and not all used this pulley set )
Motor Pulley: 18 - 30 - 42 mm
Intermediate Pulley: 18 - 33 - 49 mm
Spindle Pulley: 55 - 70 - 85 mm
Please Note: My replacment belts will fit only the U.S. distributed models. I have heard of only one European spec. machine here in the States. European Unimats could have had either of these pulley sets!
TECH TIP:
Common replacement screw sizes:
Motor bracket screw: 5mm x 12mm long thread machine head screw. ( if too long it will hit internal parts of motor !)
Motor pulley screw: 4mm x 8mm long thread pan or cheese head screw. Include a washer here.
Motor pulley stop pin: .062" C.R.S. rod or music wire, must conform ( bend ) to inside of pulley.
I have found the local Industrial Ace hardware to have a good selection of metric fasteners.
Here is a TECH TIP from:
Robert Frear
Here's an interesting discovery I made when taking apart an old dot-matrix printer for my parts bin. The print head carriage rod is the exact diameter of the Unimat DB and SL carriage rods! As the years go by, the carriage starts looking pretty rough, and these look like a high quality replacement.
Not only that, there are stepper motors, drive belts, and other things to
make prototype CNC etc.
I dismantled two printers, a narrow carriage Panasonic and a narrow carriage NEC. Both had the same diameter rod, and were of adequate length. The older the printer, the more robust it seems, and around here, they often sell for peanuts.
Unimat Motors, Premature Failure?
In the past 12 months ( 2001 ), I have received quite a few emails regarding drive motor failures. Replacing the motor if you can find one, can be as costly as a basic unit.
Let me just pass this information along in the hope of saving a Unimat user the trials & expense of motor replacement.
All DB/SL & Unimat-3 motors have an intermittent duty or " duty cycle of 80%. ( the 80% duty cycle was gleaned from the Unimat-3 manual). If the motor becomes hot to the touch, 130 deg. to 140 deg., let cool...
Which means after being used for 8 minutes, it must be switched off for 2 minutes!
This is especially important when chucking up harder materials like steel.
Keep in mind the internal heat generated by the motor is only dissipated thru the metal case of
the motor, there is no cooling fan. Excessive internal heat will lead to premature bearing & motor winding failure.
The only exception here is the U-100 motor.
This is the gray plastic cased motor with the orange slide switch. It was supplied from approx.
68' to 74'. This is the only Unimat motor that is internally fan cooled & continuously rated.
Also I agree with Steve Jaynes, that it is the best & probably most expensive motor Unimat
provided, judging that in the last years of production they went back to the metal case motors
& plastic handles.
Unimat Chucks / Replacement Chucks / Jaw Replacement
Over the years the jaws can take a beating, especially if abused by over tighting.
Original DB/Sl jaws are hard to come by.
The chuck jaws for the Unimat DB/Sl and The Unimat 3 were the same. ( the chuck spindle thread was different, 12 X 1 mm for DB/SL, 14 X 1 mm for U-3 ). The Unimat 3 is now the Taiwanese made Unimat 4, there are also Taiwanese knock-offs , the MJ189A and Combi-218.
Note: Unimat DB/SL spindle thread 12 x 1 mm
Unimat 3 / 4 spindle thread 14 x 1 mm
Also, keep in mind that Sherline makes replacement chucks with Unimat threads.
Unimat DB/SL 12x1 thread,
#1068 three jaw chuck and # 1071 four jaw chuck
Unimat-3 14x1 thread
#1031 three jaw chuck and #1035 four jaw chuck
Here is a TECH TIP from:
Richard Hall
" WW " Watch Makers Spindle Belts
The regular small belt fits from the motor pulley to the idler (this is no different from the normal spindle) and the power feed belt fits from the idler to the main spindle pulley. This main pulley is much smaller than the one on the regular spindle. For belts, See my belts & accessories page
Here are a couple of pix of the UG-7750 motor.
With date code: 12 / 86 .
A latter replacement motor for the U-90.
Clearly illustrated is the duty cycle rating.
In this case 60% 6 min. on / 4 min. off
Pix credit , John Rawley
More motor information
The U-90 and U-7750 motors have self aligning oilite or bronze bearings. I don't believe replacements were offered.
The U-100 motor has ball bearings, which are replaceable.
DF 2009
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TECH TIP:
Redford Green
To clean the internal threads on chucks etc. on the Unimats I use a bronze shotgun cleaning brush.
12 bore is about right for the Unimat 3/4 and 410 for the DB/SL
TECH TIP:
Jude
A quick tip for anyone looking for some high-quality Tommy bars. Locate a couple of old 5 1/4" floppy disc drives (remember those?) and take them apart. The guide rail for the head is 3.70" long and .158" diameter and fits the holes in the 3-jaw chuck perfectly. If you work at a large company, ask your PC techs if they have any, or try a used computer store. They will probably give you a box full of drives just to get rid of them. As a bonus, the body is fairly good quality aluminum you could use for small projects.
Spindle Nut Removal:
Sometimes the spindle nut can refuse to come off, ( not a supprise, after 30 or 40 years of being locked in place ). In the process of holding back the shaft, the nose threads and or locking hole can be damaged.
Here is a proven way to loosen the nut and not damage the assembly.
Works for both standard spindle & "WW " spindle cartridge.
Soak the lock nut with WD-40 or the like for a couple of days, tap on the flats of the nut ( a piece of
flat stock, brass ) Hold back on the pulley, it's the largest surface, covered with a piece of split vinyl
tube. Use 19MM wrench , rap on wrench with mallet. It will give.
Here is a handy speed chart, for both the standard pulley drive and the slow speed or double reduction pulley drive.
The slow speed drive has two idler pulleys. It delivers twice the power at half the speed for turning large work or threading.
Note: the motor pulley is on the right of the chart. It can be removed and reversed on the motor shaft to deliver the speed indicated on chart.
The last two diagrams 12 & 13, show the slow speed drive ratios.
TECH TIP:
Richard Ashley
I have a small tip to pass on to you and other Unimat users. I use the diposable plastic cup shaped covers which protect the spring connectionsons on 6-volt lantern batterys when purchased, as a means of protecting the threads on both the headstock and tailstock spindles when not in use. The cone shape presses on nicely and stays put while not harminng the threads therefore protecting them from damage.
TECH TIP:
Motor bearings
Ray Humphries
Not long ago you really helped out with a Spindle repair. I have some info I thought I would pass on ( obtained from tips, luck and experimenting); "636 ZZ" this is a ball bearing that fits just right in the bearing socket of an older Unimat motor. OD 22mm, ID 6mm & width 7mm. I had to experiment a little with the spacers and pre-load washers but I did get a 0.25mm endplay taken up by the pre-loads. My motor just zips along now.
Spindle Removal:
The spindle can be removed as an assembly.
Loosen the two 5MM socket head screws on the head, remove the small slot head screw / pin, remove pinion lever.
Loosen clamp that holds the spindle to motor bracket. The spindle W/pulley & spring can now be removed from the back of head, away from tail stock.
If the pulley is turning you may hold back with the spindle lock hole to loosen nut, be careful not to distort hole.
Clean all parts with solvent and re lube.
Mini Chuck
Harbor Freight has a 2" mini three jaw chuck with a Morse taper arbor. Unscrew the arbor and the chuck screws on the the Unimat DB/SL spindle, ( 12 X 1 MM ) .
www.harborfreight.com item # 4486-8VGA .
Update 7/29/08, it's still available. I just bought one. It is a perfect fit. It is stiffer than the Unimat chuck but will probably easy up with use. Not as fine a finish as the Uni chuck, but for $28.99 I have no complaints. Fred Mobley
I thought I would pass on another source for 3-jaw chucks for the Unimat. I just got one from Wholesale Tool, www.wttool.com item # 3003-0100. I installed it on my old "green hammertone" lathe and it fits and works
fine. Its pricier than the Harbor Freight chuck but then it also comes with MT1 and MT2 arbors, plus a couple of nice knurled tommy bars. Dave McFadden
Motor Brushes
Campbell Tools offers replacement brushes for the the Unimat motors
Here is there website http://www.campbelltools.com
Motor Runs Backwards
I have had a number of emails about motors running backwards. Emails from Unimat users have suggested that the rotation reversal has to do with motor capacitor failure. I will post more info. when available.
Here is a recent email I received from Art Bell. This will shed some light on the motor runs backwards problem. Thanks, Art...
Power Feed Belt:
Sometimes you will find the pulley of the Power Feed attachment does not align with the take off pulley on the spindle. No problem! Just advance the spindle with the quill lever and lock the spindle in place with the two clamping, socket head screws in spindle head. You will need this alignment when you cross the power feed belt to reverse the feed for left hand cuts, toward the tailstock...
Cutting Right / Cutting Left:
I know this is basic, but I will review it here for those not familiar and to help with any confusion....
Right hand cuts; Is the most common cut, it means you are cutting left towards the spindle!
The tool bit would be identified with ' R ' example ( AR-4 ).
Left hand cuts; This means you are cutting right towards the tailstock!
The tool bit would be identified with ' L ' example ( AL-4 ).
Good to know when ordering cutting tools or grinding your own cutters!
TECH TIP:
Danny Bynum
Really enjoy your website.
Thought this tidbit might be of interest to other UNIMAT users:
I’m always on the lookout for a nice (and cheap) source of shim material for my tool post. I recently discovered
stock that measures .026 thick and is .312 (5/16) wide made of mild steel. This just happens to be the depth of
my UNIMAT 3 tool holder slot.
If you’ve ever worked in an office then you’ve probably heard of a hanging file folder called “PENDAFLEX” or “FILE-PRO”. Well, the metal strips that support the heavy paper folder are made of this material. Usually 13” long for letter size. Ask around and you can probably get one for free…….You only need one.
I used a small metal shear at work to clip off shim strips about 1.25 inches (32mm) long. The shear left a nice square, but sharp edge that needs to be rounded off a bit. You might be able to use a Dremel cut off blade for the cuts. I’m sure there are a few different ways to make a nice cut.
( This should work equally as well for the DB/SL tool holder, Doug )
The Most Common Unimat DB/Sl Motors
U-90 Motor. Probably the most widely used motor.
This is a well made motor with large oilite bearings.
To service; first unscrew brush caps, remove carbon brushes ( make note of orientation, must go back same way ), mark case where it splits ( must go back same way ), remove nuts front of motor ( 7mm nut, a cheap 9/32" x 1/4'' socket with the O.D. ground to fit, works ).
Split case, watch orientation of internal washers. Clean, oil bearings with light oil then I lube shaft with Lubriplate (machinist lube, a light lithium / moly base grease ).
Put back together in reverse order.
These motors are old. Do not hesitate to service them. It will be more costly to replace them later.
Before servicing motor disconnect from electrical power!!!
Note; Before disassembling any of these motors. You need to remove the pulley stop pin and clean up any burrs on shaft as not to damage bearings removing case from shaft. ( see above Tech Tip, Common screw sizes, for stop pin info. )
Take your time in dissassembly, note how things go together. It will be easier in reassembly.
If you do not feel comfortable working on motors , have a local motor shop service it.
U-7750 Motor. It was used after the U-90, and remerged in the last years of production. It was also sold as Emco's final replacement motor.
Again a well made motor with large oilite bearings.
To service; first unscrew brush caps, remove carbon brushes ( make note of orientation, must go back same way ), mark case where it splits ( must go back same way ), Unscrew bolts from front. Split case, watch orientation of internal washers.
This motor has wiring in front and rear of case, careful.. Clean, oil bearings with light oil then I lube shaft with Lubriplate (machinist lube, a light lithium / moly base grease ).
Put back together in reverse order.
U-100 Motor. It came into use after the U-7750. But as mentioned above was not the final motor. The U-7750 came back in the final years of production.
A well made motor, probably their best ( most expensive ). Has internal cooling fan, rated for continuous duty and ball bearings.
Because of cooling fan,the inside can become quite dirty.
This motor is a little more complicated internally.
Remove back cover ( two screws ), first. Remove small push on terminals from brush holders ( tag / mark wires, capacitor may fall out, note placement). Pull out brush holders. Unscrew front screws, pull motor apart (there is a felt seal in front and spring washer in rear that may fall out ). Clean ,repack bearings if you can, with medium bearing grease.
Put back together in reverse order.
Motor Section
I have had a lot of emails requesting info on servicing of motors. This should help.
This section updated September 2009
Note; There were several different Dutch motors on the very early DB 200's. They are documented on other sites.
Steve Jaynes, Unimat site: http://home1.gte.net/jaynes/lathes/Unimat-SLs/Unimat-motors.html
Tony Griffiths, Lathes site: http://www.lathes.co.uk/unimat/index.html
I am covering the most common motors here.
Doug:
Here's some info for you, and a question. You state in your Tech Tips section (thanks for that, as well as your whole web site!) that the U-100 motor was the only one that was fan cooled. My Unimat, a greenish hammertone DB200 model, of which I am the original purchaser ... probably bought new somewhere between late `59 and early `60 as best I remember ... is fan cooled but is not the U-100. Instead it's a made in Holland motor, labeled Motern Eindhoven, 2800 RPM, 125 Watt unit. The addendum pages supplied with the manual are specific to the 2800 RPM motor speed. It has a really fat capacitor housing located under the motor, to which is affixed the data plate. The switch is on the line cord. Yes, it's fan cooled and pumps hot air out the screened openings in the rear, but it still gets HOT. When the motor reaches a temp where it's uncomfortable to touch I turn it off and let it cool. John Williams
Pix of a Motoren Eindhoven made in Holland. Dutch made motor with cooling fan from Very Early Unimat DB.
Pix credit , Tony Griffiths
For more early motor and machine info. See links below to sites by Steve Jaynes and Tony Griffiths.
John, Thank you for the info. Doug
Pix credit , Steve Jaynes
Pix of Early Unimat DB with Black and Silver Dutch made motor. Motoren Eindhoven made in Holland
Updated, September 2009 with more motor servicing info.
Scroll down for motor and chuck info.
Long page, lots of good stuff!!!
Casting Changes ( here is an answer to a recent email )
The changes in castings, as you may or may not know are documented on other sites. I was never that interested in subtle production changes. I find more fun in using my machines.
There is a lot of verbiage out there about which machines are better. The verbiage I find interesting, is that the cast iron base machine is stronger ( better ). What should be noted, is that the inherent weakness of the DB/SL design, is its use of rod ways, which can distort under heavy load. The question of which base is stronger is moot.
That understood, within it's limitations it is a precision little machine. Have Fun... Doug
The Unimat DB/SL manual states that the the motor is continuously rated, they illustrated the U-90 motor, but later motors and the Unimat-3 manual clearly indicate a duty cycle rating. These motors are all of a basic similar design. Did Edelstaal/ Emco have an issue of replacements under warranty and added the duty cycle spec.?
Adjusting tool bit height ( here is an answer to a recent email )
(Again, I know this is basic, but I will review it here for those not familiar and to help with any confusion....)
I have got another question, I lock the spindle head down tight but if I try to cut to the center of a part on the lathe. The part climbs up over the tool and twists the head. How do I stop this from happening? Kurt
Suggestions:
The tool bit cutting edge height has to be dead on center of the work.
An easy way to check this, hold a piece of thin stock or ( machinist 6" rule ) next to round work and run cutter up to it with cross slide. If rule stays straight, you are OK. If rule turns back or forward, you need to adjust the cutter height with shims until rule stays straight.
The end of the work is moving, because it is not supported. You need to center drill from tail stock and then support end with live or dead center, Use a steady rest, Make sure tools are sharp. When cutting steel, go easy. Doug
Thank You, to the many Unimat enthuisasts from around the globe for your help!......
Remove and clean all parts:
A solvent base cleaner is good. A citrus base cleaner is OK, just be sure to completely dry parts after rinsing.
Lube bearings with a medium bearing grease. A moly (molybendium) or dark base grease like cartridge grease found at Auto Parts or Hardware store.
I would not use lithium (white) base grease or Lubriplate as they do not hold up at high speeds.
Now reassemble.
NOTES:
1. 1st bearing (pulley end) should be free to move in housing.
2nd bearing (nose end) outer race can sometimes be difficult to remove from spindle cartridge.
2. The pulley compresses the preload washers thru the first bearing.
The sleeve transfers preload to second bearing.
3. Use chip board “cereal box” shims to space motor bracket off of pulley, slight misalignment with idler pulley is OK. Tighten lock bolt and remove shims.
4. Snug down pulley nut tight. All axial play is taken care of with proper preload washers.
Pix of an Early Unimat DB (mid to late 1950's) with another version of the Motoren Eindhoven made in Holland. Black Dutch made motor.
This is a very nice original cast iron DB 200. Notice it has the machined "key" slot for spindle head alignment.
I like the look and feel of these early machines.
Pix credit , Brown Hawkins
Unimat DB/SL motors run clockwise as you face the motor pulley. The spindle turns down towards the cutter.
Here are generic wiring diagrams ( series wound and parallel wound ) for universal motors like the Unimat motor.
Hi Doug,
As a moderator of the Yahoo “Unimat” group we are often referring our members to your excellent advice and articles. I try to regularly review each site listed in our Links section to make sure the link still works and to see what has been added or changed. I noticed that you now have a “Motor Runs Backwards” heading. Over the years this subject has come up in our group discussions, and is always the result of a recent motor disassembly, with the usual advise from amateurs and experts running from reversing the power leads to reversing the brush leads to doing some of each or both. Some members merely took the motor apart, changed nothing (they thought) and it miraculously corrected itself. To try and resolve this once and for all, I disassembled my perfectly good U90 motor to see what might be a possibility. Index marked the case and the field coils to insure reassembly would go smoothly, learned little or nothing from what I seen internally and reassembled the motor again. It run reversed!! How could this be?? It turns out that while concentrating on positioning the internal leads to clear the commutator etc in the back housing, I had unintentionally rotated the field coil assembly half a turn in the housing and reassembled the motor without noticing my index mark was missing! This created the same effect as if I had swapped the brush lead positions, and reversed the motor rotation. The motor capacitor is for brush arcing and RF suppression only.
Keep up the good work. Regards, Art
