Oversized cast iron Eze-Sleeves® are made for motors that have been previously sleeved or if a mistake is made during the boring operation. The oversized sleeves allow the motor to be worked on and sleeved again with minimal cost or time loss.
The oversized sleeves are .040″ (1mm) larger on the outside diameter which allows the old bore to be opened up slightly to accommodate the oversized sleeve.
Quick and EZE. Cost Saving, Time Saving, Eze-Sleeve®
[“Abbreviated installation procedure for EZE-Sleeves®:”, “Click to hide: Abbreviated installation procedures for EZE-Sleeves®:”, “hidden”]
- Chuck and indicate the housing in the lathe.
- Machine the bearing surface to a diameter.002 smaller than the O.D. of the sleeve.
- Press in the sleeve by using the tailstock, freezing the sleeve, heating the housing, or driving it in with a hammer.
- Machine the extended portion of the sleeve to the bearing diameter.
- Once the proper diameter is obtained in the extended portion of the sleeve: finish machining the sleeve using a fine feed rate.
- If necessary, a light sanding may be used to get an exact dimension.
- Machine off the extended portion of the sleeve.
- If necessary, machine a slight chamfer to allow the bearing to enter the housing.
- The housing is now ready for assembly.
[“Detailed installation procedures for EZE-Sleeves®:”, “Click to hide: Detailed installation procedures for EZE-Sleeves®”, “hidden”]
Most Three-Jaw Chucks are not very accurate. Even if they were initially they lose accuracy with time and wear. Also, most end shields are only rough castings where you normally hold them for sleeving operations. Bearing these facts in mind, all end shields that need to be sleeved should be set up in a Four-Jaw Chuck.To locate an end bell properly in a Four-Jaw Chuck you should mount a dial indicator on the cross slide. Now grip the back of the end bell in the chuck jaws wherever it is possible. (Sometimes this may mean bolting or welding rings or lugs to the back of the end bell to grab onto.) Using circular lines on the front of the chuck as a guide, rough locate the end bell on the spindle centre line.
The first thing to concern yourself with is making sure the front face of the end bell (bearing bore side) is on the same plane as the chuck face. This is accomplished by rotating it past a tool in the toolpost near the outer edge of the end bell. Tap the end bell near the outer edge, with a soft material (lead, aluminum, brass, wood, etc.) until it is running parallel to the chuck face. This first procedure is done by eye in a matter of seconds. Now use the indicator and repeat to bring the end bell to within one or two thousandths accuracy.
Having mounted the end bell in the chuck, located it roughly concentric with the spindle bore, and dialed it in parallel with the chuck face, it is time to locate it concentric within one to two thousandths accuracy.
This next procedure can be very simple and methodical, or very confusing, haphazard and time consuming, depending on your approach. When you view the Four-Jaw Chuck from the face you will see four jaws on two axes. Let us call two jaws exactly opposite each other the x-axis. Let us call the other two jaws the y-axis.
Only adjust the jaws of one axis at a time! I repeat, only adjust the jaws of one axis at a time. If you bear this in mind at all times you will have very few problems with a Four-Jaw Chuck.
The procedure is as follows:
- Set the dial indicator to touch the outside machined lip of the end bell (checking for radial run-out.)
- Rotate the end bell to Jaw “A” position and record your reading.
- Rotate the end bell 180° to Jaw “C” position and record your reading.
- Set the zero position on the indicator bezel and the exact mid point between your high and low readings.
- Adjust Jaw “A” and Jaw “C” by alternately tightening and loosening them to move the end bell into position.
- Having completed the x-axis adjustment, repeat the same procedure for the y-axis.
- Theoretically the end bell should be completely concentric with the lathe spindle. To check, rotate the end bell past the indicator. If you find a slight run-out, adjust accordingly, keeping in mind the x-y axis theory previously illustrated.
- Double check to make sure the front face of the end bell is still parallel with the chuck face. If it is, proceed to the sleeving operations. If it is not, tap it true again and recheck the x and y axis again for run-out.
- The above procedure sounds somewhat time consuming, but in practice becomes relatively quick and easy if all operations are done in the proper sequence and the method of attack is thoroughly understood.
The next stage is the boring operation:
- Measure the sleeve O.D. at two or three locations around the sleeve and take the average.
- You should bore the end bell for a press fit. The theory for a press fit is .0005″ for 1.000″ of sleeve diameter. Therefore, a sleeve with an O.D. of 3.504″ should have a press fit of approximately .002″. A sleeve with an O.D. of 6.929″ should have a press fit of .004″. Most machinists use a .002″ press fit for all sleeves below 4.000″ diameter.
- Having calculated the diameter you wish to bore the end bell to, set up a boring bar in the tool post and take a trial cut. Measure the bore and adjust the crosslide to cut the desired diameter. This is done using the graduated collar on the crosslide handwheel.CAUTION:Diameters for press fits for sleeving and more important, diameters for bearing fits are extremely critical. All lathes develop wear and backlash in their crosslide screws and nuts. When doing boring operations where there are tolerances of ±.0002″, mount a dial indicator on the saddle with the plunger up against the tool block, in line with the crosslide direction of travel. With this arrangement even an old lathe (1920′s) can be used to do precise work. Your lathe becomes as accurate as the dial indicator.
- Having completed the bore, press in the sleeve by one of the following methods:
a) This is the safest and easiest method. Keep in your shop a cylinder of CO2 (syphon type). This cylinder type draws liquid CO2 from the bottom of the cylinder. Liquid CO2 is at -190ºF. Set the sleeve on an insulating material such as styrofoam. Spray CO2 over the sleeve for a few seconds. The sleeve will become extremely cold and consequently shrink several thousandths in diameter. Now using insulated mitts to prevent frost bite, pick up the sleeve and insert it in the housing. After a few minutes it will expand and lock itself in place.
By doing it this way the end bell set up is not disturbed, thus eliminating a second “dialing in” procedure. Also, a shrink fit has three times the holding power of a press fit. To understand this, visualize a bolt being pressed through a nut. The threads of the bolt and the nut will be sheared off leaving very little holding power. If the bolt however was shrunk enough to be inserted into the nut and then expanded to mesh with the threads of the nut there would be a much greater holding surface. This happens with a sleeve at a microscopic level because even a ground finish has minute irregularities which embed themselves into the housing bore.
b) Press the sleeve in using the lathe tailstock spindle.
c) Hammer the sleeve in with a soft material such as aluminum.
d) Remove the end bell and use a hydraulic press to insert the sleeve.
e) Heat the end bell with a torch.
Letters b, c and d have the obvious drawback of having to reset the end bell, plus an inferior gripping of the sleeve in the bore.
Letter e has several problems: it takes time and gas to heat the end bell; heating the end bell makes it expand against the chuck jaws; distorting them. After the end bell has cooled it may become loose in the chuck. You have to wait for the end bell to cool to room temperature before finishing the bore. Sometimes heating end bells can leave them permanently distorted.
Finish machining of sleeve:
After the sleeve is installed in the end bell you start the finish boring operation. Use the same boring procedure that was used to machine the end bell to accept the sleeve.
Usually there is a small portion of the sleeve protruding out of the housing. Take a trial cut on this portion of the sleeve only. Measure the diameter and adjust accordingly and take another trial cut. Once you have reached your desired finished diameter in the extended portion of the sleeve you may safely proceed to finish the bore using a fine feed. Sometimes a light sanding is required to improve the surface finish.
Now machine off the extended lip and add a slight chamfer to allow the end bell to start over the bearing. Your repair job is now complete.
[“Common questions & answers for EZE-Sleeves®:”, “Click to hide: Common questions & answers for EZE-Sleeves®”, “hidden”]
40 thou. left to machine off.2. What is the minimum or maximum press fit?
2 thou. —–formula: 1/2 thou. per inch on diameter.3. What is the shrink fit between the sleeve and the shaft?
2 thou.4. What is the thickness of the sleeves?
1/8″-1/4″ for the larger sizes.5. What is the Rockwell hardness of the cast iron?
25-30 Rockwell.6. Why is the I.D. of the sleeve not finished?
If there are any problems pressing in the sleeve,For example:
a) housing is not bored for an exact .002″ press fit
b) minute dirt particles get between the sleeve and housing
c) sleeve is pressed in crooked, etc.
The I.D. of the sleeve will change or distort. If this happens, bearing failure is inevitable.