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 dissasembled and the bearings regreased. To do this remove the spindle cartrige 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.
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:
If you have a Sears Unimat Model# 736.21410 it is the same as the Unimat DB200.. 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 in the last several years of selling replacement belts.
Thanks to the many Unimat enthuisasts from around the globe......
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%. 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-775 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 motor has self aligning oilite or bronze bearings. I don't believe replacements were offered.
Also the U-90 has a thermal overload in the motor winding, which opens up when the motor becomes overheated, then resets when cooled off. This can be a source of failure.
The U-100 motor has ball bearings, which are replaceable.
DF 2008
 | ||||||
E-mail: dfeistamel@comcast.net
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
Remove & clean all parts:
Outer race of bearing on pulley end must be free to move in headstock. Preload washers must be dished.
Lube bearings with medium bearing grease & reassamble.
Note:
1 The pulley compresses the preload washers thru the first bearing, the sleeve transfers the preload to second bearing.
2 Use chipboard shims ( cereal box ) to space motor bracket off of pulley, tighten motor bracket allen head cap screw then remove shims. Slight misaligment with idler pulley is normal.
3 Snug down pulley nut tight, all axial play is taken care of with proper preload washers.
Motor Brushes
Campbell Tools offers replacement brushes for the the Unimat motors
Here is there website www.campbelltools.com
Motor Runs Backwards
I have had a number of emails about motors running backwards. I can only guess at why.
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. You will need to open up the motor and see what you have. Then change connections.
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 )
