A Photographic step by step prodecure I used for pouring new babbitt bearings
This is my first attempt at pouring Babbitt. This is part of the restoration process for my 6 HP Ohio, however this step was so involved I thought that it would be better as its own topic. I know there are most likely better ways to do this. It came out OK and I learned a whole bunch. The photos and the text that follow show how I proceeded with this task.
This photo shows the original bearing in its terrible condition. You can see why it needed replacing.
Removal of the old Bearing. It was really attached !!
The pockets Cast into the base to hold the babbitt were quite effective. I had to use a drill and then a torch to melt out all of the remains of the origial bearing
The next step once the casting was clear of old babbitt, grease, oil and dirt was to drill and tap provisions for two leveling screws at each bearing location. They were made of flat head brass machine screws and worked perfectly for positioning the crank shaft in the proper position. Once the bearing is poured they will be removed and plugged with normal set screws so the unsightly screw heads are no longer seen. I learned this trick from the boys in Pavilion, NY and what a time saver it is. Thanks to Stiles Bradley and Craig Prucha
Measuring for the covers that will mold the split line of the babbitt
Machining the covers to length in the milling machine. Made from 1/8 scrap steel I had laying around
The crank shaft cleaned and ready with polished journals
Applying the "Release Agent" to the shaft. This is real simple process. Just crank the Acetylene without any O2 and apply the carbon to the shaft. I would suggest you do this part outside as it fills the air in the shop with black floaters
The shaft after applying the "release agent"
The sooted crankshaft in the crankcase in its proper position. A lot of time is spent here making sure the crankshaft is centered side to side in relation to the cylinder bore. Also it needs to be perpendicular to the cylinder bore and least but just as important the height of the shaft is criticle so the side shaft bears will mesh properly. This takes time but is all done with the two brass jack screws that were installed into each be of the bearing housings
The covers are shown here in position
The Covers secured in position with sleaves cut to length held in position with the bearing cover stud nuts. The Hole on the Bottom will become the fill hole where the babbitt is admitted. The two holes on top are vents where the excess babbitt will exit.
With a majority of the mechanical preparation done. it is time to get ready for the pour. The next step is to Dam the bearing assembly so when the molten Babbitt is poured, it does not leak out the sides. A thick sticky flame proof putty is used for this - brand name Babbitrite and can be purchaced from McMaster Carr
The next several pictures show the putty and how it was applied. Also the Babbitrite was used to make a funnel to help guide it in when poured. It is nasty stuff and resembles Goose Poop but worked as advertised.
With all of the preparation done the main task is at hand - melting and pouring the Babbitt. The next photo shows the Babbitt in its bar stock form. This is available from McMaster Car Industrial Supply as well. The alloy used was the softer variety which consists of 80 1/4 % lead and 14 3/4% Tin
Close up shot of the bar and its composition
The next two shots are of the babbitt - cut into apropriate length pieces and the apparatus used to heat it.
The Babbitt is heated to a temperature of around 750 degrees F. Not shown - but we used a hand held digital pyrometer to check the temperature. This is a simple device which I borrowed from work . These are reletively inexpensive and cost about $100. Easy to use, just aim and point to the surface you want to check. A red Laser built into the device helps aim it. Accurate within 1 degree or two
Now while the Babbitt is heating it is time to preheat the bearing housing and crank shaft. For this I used a 200,000 BTU hand held propane torch. This really puts on quite a show. Even with all of its available heat it still took about 30 minutes to get the iron up to temperature so it was safe to pour. With doors partially open for ventilation the temperature in the shop went up over 15 degrees while doing this! If you follow what is written in the published babbitt pouring guides, the base metal should be preheated between 430 and 500 degrees and the shaft around 300 degrees F. This may not be practicle but the idea here is to heat it to remove all available moisture as this will be disasterous when pouring and to keep the babbitt from cooling too rapidly once poured.
It is very important to have at least one good fire extinguisher handy before you get to this step. I had two 20# Halon units at arms reach. If practicle, do this whole process out of doors. The day I did this it was 40 degrees and rainy with a 25 MPH wind - so it was either wait for another weekend day when I happened to have time or move the whole operation inside - as you can see it was done in my garage
Babbitt at temperature ready to pour.
If new fancy temperature reading instruments are not handy the old stand by method is to put a small pine board in the molten babbitt and stir for a second or two, remove and if it comes out blackened from the heat, it is ready.
It is also important to stir it as this helps remix the three elements in the babbitt alloy which tend to seperate by density when molten.
Before pouring, scrap the crust or impurities off of the top to prevent from going into the new bearing
After the pour - as you can see things got hot !!
After removal of the Babbittrite and the funnel
The Finished product and hand deburring. They came out fairly well for my first attempt. The next step is to hand scrap the bearings to achieve better than 80% contact. This is a process where by the crankshaft is lowered into the bearings and rotated. The areas where it contacts the babbitt will become shiny. These shiny spots are carefully scraped with a babbitt scraper removing the slightest amount, then the whole bearing dulled with a scotchbright pad. The process is repeated again and again until the shiny spots account for more than 80% of the total width of each bearing. For this crankshaft the process was repeated about 20 times (almost a whole afternoon). When done and with a few drops of oil applied the crankshaft will rotate for several minutes when spun by hand. Nothing like a good babbitt bearing !
The last step was to remove the brass jack screws and replace with set screws. These are secured with Locktite amd set so the ends are about 3/16" away from the shaft surface
Other than cutting an oil grove in an "x" pattern in the bottom of the bearing we are ready to continue with the restoration process.
I used the following book as a guide and found it most helpful. Bought it on ebay for under $10.00 - worth every penny
HOW I POUR BABBITT BEARINGS
Written By Vincent R Gingery
Published by David J. Gingery Publishing LLC
Soft bound - About 45 pages
PO Box 318
Rogersville, MO 65742
Copyright 2001 ISBN 1-878087-24-X