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Brown and Sharpe 618 Micromaster - useful info

GeneT

Cast Iron
Joined
Feb 21, 2002
Location
Albany, OR 97321
Howdy all,

I've been bringing a new-to-me B&S Micromaster 618 online and thought I'd share the info I've found. Some of it is from PM, some from disassembly, and some from investigation. I'm hoping to consolidate it all in one place and perhaps gather some additional information / correction at the same time.

Lube: Mobil Vacuoline 1405

Oil metering units: (Based on what I pulled off my machine):

Bijur fittings
(I'm using X, Y, and Z as on a mill - I've seen some indication that this might not be the standard for grinders).
qty 2 Bijur MJC #5 for the X ways,
qty 2 MJC #5 for the Y ways,
Qty 2 MJC #2 for the Z ways.
qty 1 MJC #2 for the hypoid gears
Qty 1 MJC #0 for the elevation leadscrew, Qty 1 MJC for the hypoid gears

Total: 4 x #5, 3x #2, and 1x #0

Filters: This one is a bit tenuous. I couldn't find anything directly, but I found an auction lot of filters "for a 618 MicroMaster" and after combing the catalog, based on what I could read, figured they must be a Baldwin F902C1. That's an obsolete filter (of course) but Killer Filter had a replacement: Killer Filter: F902C1 BALDWIN Filter Replacement (104-3525). The replacement almost works. If you pry off the top (cork) seal retainer it fits. That's a 15u filter. DoAll uses a 10u filter, but it's the best lead I've had and it's what I'm running at the moment.

Spindle belts: If you're running an "Oriflex" drive, the belts are #431 Buna-N 90 durometer o-rings. (Amazon had these for less than $12 for a pack of 10, the MM takes six...)

Hope that helps!

GsT
 
This is an old thread, but since people use these threads for reference I wanted to note that the Oriflex drive O-rings are actually not #431 Buna-N's. They're close, however the cross sectional dimension of the B&S ones is ~.250", while the #431's are .275". This results in O-rings that are very tight in the Oriflex pulley and on my machine run roughly.

The #431's may well work fine for you, this is just FYI in case you find as I did that the #431's rub on the pulley, get hot, etc.

I have yet to find a reasonably priced B&S equivalent (H&K want $24/each!).

-Phil
 
Yeah I actually feel bad that when I called B&K and they offered me the set of 6 for $100 I didn't take it as that seemed too high. I have been using the #431 O-rings and get some odd things going on. Like the belts are binding up. Seems anything over a really light cut will cause the motor rpm to drop quite a bit.

Another thing I was very surprised about this thread is no mention of spindle bearing type. I have a later unit with two matched sets of bearings and mine are howling and need to be replaced. Still grinds a very nice finish just requires hearing protection and only with no one else around. Not very usable.

Does anyone know the bearing model #? 7007 or ?.

I know they are matched sets and not sealed or even shielded but stupidly didn't take notes when I had mine out because I was trying to repack them to see if I could avoid spending the money on a new set. Don't want to take them out to look as the machine still works, just very annoyingly.
 
Yeah I actually feel bad that when I called B&K and they offered me the set of 6 for $100 I didn't take it as that seemed too high. I have been using the #431 O-rings and get some odd things going on. Like the belts are binding up. Seems anything over a really light cut will cause the motor rpm to drop quite a bit.

Another thing I was very surprised about this thread is no mention of spindle bearing type. I have a later unit with two matched sets of bearings and mine are howling and need to be replaced. Still grinds a very nice finish just requires hearing protection and only with no one else around. Not very usable.

Does anyone know the bearing model #? 7007 or ?.

I know they are matched sets and not sealed or even shielded but stupidly didn't take notes when I had mine out because I was trying to repack them to see if I could avoid spending the money on a new set. Don't want to take them out to look as the machine still works, just very annoyingly.

Mine is a B&S 510 but this may apply...

I have original O-rings and also tried replacements that were 431’s as you have. I found the 431’s were too tight on the pulleys and created friction/heat/vibration since the bound rolling off the pulley. The originals are much smoother due it seems to about a .240” cross section diameter while the 431’s seem to be .267”-.275” so very tight on a pulley that is .267” or so ID of each pulley slot.

In another thread I mentioned the bearings on my spindle were a single pair of New Departure Bearings Q0L07 DTX 7097. These are effectively like 7007 P4Y bearings, but with ground races for the specific preload config.The preload on the bearing was “light” but the NDH grinding code suffix (the X in DTX) seemed to suggest medium. The NDH’s are 15degree contact angle, and mine are in a back-to-back arrangement with a long spacer for the outer race, precisely matched to the bearing shoulder distance.

I was going to replace with modern universally ground 7007’s, but so far cleaning and re-greasing the originals seems to be ok for me. I was also not totally sure I could reproduce the right preload on the first try given the ambiguity of the NDH labeling. New bearings were looking like $120/pair from eBay (unsure if counterfeit or not) to $300/pair from locatebearings for NTNs, to $800/pair from a local bearing supply (********* bearings). All P4 / ABEC 7 or P4Y.

Phil
 
Yeah just checked eBay and there are matched sets of SKF for about $120. So assuming they are 7007's then I ran into the next issue. There are like 3 different listed 7007 matched sets. Each with a alphabet after the bearing number. Trying to refer to the online bearing naming charts didn't even get close. The ones on eBay have like 8 letters or numbers after them.

Given that I still don't know exactly what number they are other than being unshielded and angular ball type I would be apprehensive to just buy a set blindly.

If anyone knows the actual exact bearing number for a B&S 618 Micromaster with the dual matched sets for an Oriflex drive that would be fantastic.

Thanks a lot guys.
 
I bought 1/4" urethane drive belt material on ebay. Just cut to length and melt the ends together. The regular o-rings would crack and break in about a year but I haven't broken any urethane ones and they've been on for at least 3 years.
 








 
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