# I think I am going To part out brown and sharpe 618 micromaster surface grinder



## Playingwithmetal (Feb 2, 2017)

I bought a 618 micromaster by brown and sharpe with unseen.  The machine is in good condition but needs parts that will cost more than the machine itself.  I think my only way to get my money back from it is to sell the parts to other people that are in a similar position.  It is the manual version and has most original parts and most are in perfect condition.  Any thoughts would help.


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## 4GSR (Feb 3, 2017)

I have the 612 Valuemaster version of that surface grinder.  The  Micromaster is a hydraulic actuated table version.  You sure it's that or the Valuemaster version of the grinder.  Also, can you provide the serial number and some pictures?  Yes, I would be interested in some of the parts on your SG.
BTW, what are you needing to replace?  If mine compadible to yours, I'm more than welcome to make drawings of the parts needed so you can get parts made or make the parts  yourself.  Ken


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## Playingwithmetal (Feb 3, 2017)

It is a manual micromaster 618.  I think someone must have knocked into it with crane or knocked it over.   The y axis screw assembly is bent.  I called the people that own brown and sharpe and just for the screw it would cost $800.   They're are a few other  parts that are done as well.  But the bulk of the machine is in excellent shape and doesn't look like it ever saw a production environment.


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## 4GSR (Feb 3, 2017)

that's a higher s/n from mine, but the patent numbers are throwing me off, they quit listing patent numbers way back in the late 1960's.  Need more pictures, not telling us much here.  If all is damage is the cross feed screw, that's an easy fix.  I made a new threaded section for mine and spliced it into the old screw to replace the worn out threaded part.  In your picture no. 4 shows the shifting lever for the hydraulic version.  Did someone trash out the hydraulics to the SG?


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## Playingwithmetal (Feb 3, 2017)

No the hydraulic version had a second lever control on the table.   This is the manual version.  The entire cross feed screw and all components are bent together.   The head must have been knocked pretty hard.  I am unsure how to fix.  What would you like a pic of?


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## 4GSR (Feb 3, 2017)

Lie to see pictures of the front of the machine, both sides, and the back of the machine.  Maybe a pic or two of the damaged areas, not too close up.  Ken


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## TakeDeadAim (Feb 4, 2017)

If it is the screw and associated parts that are bent, with no castings cracked or broken the machine can be repaired.   If your not up to making the screw and nut perhaps someone would help, if not and I can see photos of what is bent I would be interested in the machine to do the repairs


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## Glenn Brooks (Feb 4, 2017)

There are threads describing how others straightened similarly bent lead screws. Either here or on Chaski,org.  Can't remember which.  All might not be lost.  Keep turning over rocks, you might find a way forward. 

Glenn


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## Playingwithmetal (Feb 4, 2017)

Thanks all for the replies.   Will take more pics when I finish work today.  If any of you know the link to the threads about straightening the lead screws please plots link.  
Thanks for all the replies.


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## Playingwithmetal (Feb 4, 2017)

So the cross feed is so bent that the head is not resting on the ways.  I am unable to move the table far enough to access the hex cap screws that hold it on.   I do not have the manual so I don't know all the components.  Not sure how to remove the cross feed screw with the positioning of the table.  Any thoughts would help.  
Thanks


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## 4GSR (Feb 4, 2017)

Your's was like mine when I bought it.  Full of crud and no telling when the last time it was given a bath.  Spent about a week cleaning to get it half way decent to work on.  My Valuemaster has similarities to the Micromaster that I maybe able to help you a little.  The hand wheel for the cross feed should come right off after removing the nut holding it in place as it looks like you have already done.  May take a little gentle persuasion to get it off.  Once off, there is a plate that bolts to the housing that has a bearing in it that the cross feed screw rides on.  Again, this should come off with little difficulty.  The crossfeed screw floats in this bearing so there should be no retaining rings or such to worry about.  Once the plate is out of the way, that should leave the crossfeed screw to remove.  Next, got to the back side where the bearing block is shown in your picture 4414.  And it shows you have removed the nut and one of the thrust bearings, which is good.  Next in picture 4416, there is a mechanical stop nut secured to the leadscrew.  Remove the set screw securing this stop in place and then thread it to the end next to the bearing block. Now go back the the front of the grinder and start rotating the cross feed screw to remove.  With the front bearing removed, this should make it easier to remove.  Once the back end of the screw exits the bearing block remove the other thrust bearing and stop nut and continue until you have the complete screw removed.


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## Playingwithmetal (Feb 5, 2017)

So when the cross feed handle is removed all I see is the bearing and nothing to unscrew.  I removed the cap screws from the handle block and think the whole assembly is supposed to come off but don't want to force anything.  They're is paint and Bondo covering the seem.  If they're is a seem?  Lol.  
Thanks.


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## 4GSR (Feb 5, 2017)

Yep, your's a little different.  But, you almost have it.  That flange looking deal that you pulled the four screws out of is dowel pinned in place so it will be a little difficult to get off.  See if you can pope it loose at the top with a screwdriver and hammer.  Yeah I know, not suppose to use a screwdriver for a prying tool, sometimes you have no choice.  Once you get the seal broke loose holding it in place, should pry right off.  Get it out of the way, that should give lots of room for removal of the screw.  The screw being bent is going to make things that much more difficult to remove. Keep at it, your getting there.  Ken


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## Playingwithmetal (Feb 8, 2017)

Thanks.  Ken.  
    It fought me every step of the way, but finially got the bent lead screw.  It is so bent i don't see how I could straighten it. Here are some pics.  Any thoughts would be appreciated.    The screw is longer than my lathe and I don't have a surface plate big enough either.  
Thanks


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## 4GSR (Feb 8, 2017)

Wow! that's bent. 

I'll dig up the pictures of my repair I did to mine and get them posted sometime today.  It's very similar to yours, and I did the repair on my 9" South Bend lathe, too.

Ken


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## FOMOGO (Feb 8, 2017)

Wow! is right. Really not much to loose at this point. I've had pretty good luck with V-blocks, and a dial indicator on the press for shafts of different types. Start at the back and work your way forward. Will be interested to see how Ken went about it. Having it between centers might be good for fine tuning. The alternative would be to turn a new one, or new sections I guess. Should be interesting to see the threads the shaft turns in. If it wasn't forced after it was damaged they may be serviceable. Mike


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## 4GSR (Feb 8, 2017)

Here's the pictures of the repair I did to mine.  I chopped off the worn out threaded section and spliced in a new threaded section.  T.I.R. end to end is within about .003".  I drilled, bored, and reamed a hole in the solid part about 1-1/2" deep.  Dont remember the exact size of the reamer, 5/8" sounds about right on mine, yours may require a different size.  The OD of the threaded section on mine is .875" and is a 10 pitch full Acme thread.  (I can help you on thread dimensions if you need any help)  The threaded section section was made from a piece of .875" OD 1018 cold drawn bar, purchased locally, cut  off to the length needed, plus a little for trimming.  You need to use a follower rest on your lathe if you have one.  An option to this is to purchase a piece of 7/8-10 Acme all threaded rod.  The OD and pitch may make it difficult to find.  Of course, you really need a class 3C grade thread to get something of reasonable precision.  A class 2C or 2G will work, but maybe a little sloppy with your nut.  I also have pictures cutting the thread too if you want to see them too, just let me know.  Ken


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## 4GSR (Feb 8, 2017)

Oh, I forgot to mention, on the splice, I used a couple of tapered pins to secure the two pieces together.  Ken

Here's the pictures on making the threaded portion of the screw.


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## Playingwithmetal (Feb 9, 2017)

Wow.  Great job ken.  That looks great.  Does it travel smoothly ? 
I may have to buy all thread.   I have a mini cnc lathe 11.6" between centers and a chucked that doesn't have threading gears. I may try to straighten between v blocks.  It somehow doesn't have any damage to the threads.  I don't understand how.  Does the adapted lead screw function properly? 
thanks for all your help.


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## 4GSR (Feb 9, 2017)

The screw travels very smoothly. I have no issues with the function of the new screw.  

How about posting the specifications of the thread on your screw?  The OD and pitch of the thread and is it right hand or left hand lead thread.  Oh, about how long is the threaded section?  Maybe we can help you find a donor or a source for a piece of all thread for you.  Ken


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## GarageGuy (Feb 10, 2017)

You can buy Acme all thread.  I have a couple pieces in my stock pile.  Then cut and splice to fit your needs.

GG


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## Playingwithmetal (Feb 13, 2017)

Hey.  Thanks for all the replies.   It's been a busy week.  Finally got the time to properly measure the screw.  The screw measures 7/8 0.875".  X 10 tpi.   I think I need to make and splice as opposed to bending.  I do not think that I will be able to bend it back to acceptable tolerance.  
Thanks


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## 4GSR (Feb 13, 2017)

Playingwithmetal said:


> ....snip....  The screw measures 7/8 0.875".  X 10 tpi.   I think I need to make and splice as opposed to bending.  I do not think that I will be able to bend it back to acceptable tolerance.
> Thanks


That is the same diameter and pitch of my screw.


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## Playingwithmetal (Feb 14, 2017)

Since it's too long of a section to turn on my mini cnc lathe I will have to order a section.  I will need to order it a bit long and turn down the ends to make the splices into the other components.  I have not cut my scew yet but when I do I will indicate the non threaded section of the shaft and see it somehow it didn't bend.  I can not see any visible how to that section but we'll see.


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## Playingwithmetal (Feb 17, 2017)

Hey.  I think I am going to order the threaded section and turn down one end and bore the other for the splice.  There are a couple different variations of acme precision all thread.  This seems to be the place to get it.  https://www.mcmaster.com/#precision-acme-lead-screws/=16egto5
What item number is a match to the value master series you have 4gsr? I just want to make sure I get the right one.  Also any tips to turning down one end of the hardended all thread? Also I'm thinking of making a simple aluminum collet to hold the thread rod while lathe operations take place as to not mar the threads.  Any tips would be appreciated.  
Thanks


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## GarageGuy (Feb 18, 2017)

I don't think it will be hardened steel, it should be soft.  A regular collet will work fine.  They work great on 60 degree threaded parts without causing damage, and Acme threads are flat crowned which makes it even better.  You should be good to go.

GG


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## 4GSR (Feb 18, 2017)

Playingwithmetal said:


> Hey.  I think I am going to order the threaded section and turn down one end and bore the other for the splice.  There are a couple different variations of acme precision all thread.  This seems to be the place to get it.  https://www.mcmaster.com/#precision-acme-lead-screws/=16egto5
> What item number is a match to the value master series you have 4gsr? I just want to make sure I get the right one.  Also any tips to turning down one end of the hardended all thread? Also I'm thinking of making a simple aluminum collet to hold the thread rod while lathe operations take place as to not mar the threads.  Any tips would be appreciated.
> Thanks



My Valuemaster SG uses a 7/8"-10 pitch Acme RH Thread.  I don't see anything listed for that size.  I'm sure 1"-10 would work but you'll have to rebore the nut thread to fit the larger thread.  That is a fairly thick nut B & S used on their grinders.  Should not be an issue to open up to 1" if you desire to do so.  No need to get anything better than 1018 steel for the screw.  That's all I used for making a new screw.  B & S probably used 1215 material for the screw originally.  It's too soft to be anything better!  Don't over engineer it!  It don't have to work for a living ever again.  Ken


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