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Fasttrack
12-28-2016, 06:58 AM
I have an opportunity to buy a B&S #2 surface grinder. I don't know much about it yet and - frankly - I don't know much about surface grinders period. I've been reading up on the #2 on Lathes.co.uk (http://www.lathes.co.uk/brown&sharpeno2grinder/) but I have some general questions I thought I would pose to the brain trust here:

1) If you own a surface grinder, how often does it get used? If you don't own a surface grinder, do you ever miss it? I would have to rearrange my shop plans to get this guy to fit so I'm on the fence about whether or not I really need one.

2) Is there anything special to look out for when buying a used surface grinder? Looks like the #2 came with either sealed roller or plain bearings. Any preference? I lean towards roller bearings because they are more familiar to me and I would expect them to be easier to replace but probably much more expensive to replace (seeing as how they probably need to be ABEC-7 or ABEC-9?)

3) What do you expect a used #2 to go for in your area?

Mcgyver
12-28-2016, 07:19 AM
I'll be the computer in the Douglas Adams book that generates the rational that supports what you want to do :)

1) How many machine shops have you been in that don't have one? Use is less than the lathe or mill of course and for non commercial work you could go forever without one....but it does open up new possibilities as well as new level of accuracy and finish. Yes, you really need one :). If you discover you never use it, you can sell it, so if its not a basket case there really is no reason not to. How's that?

2) I'd share your sentiments, but that might be partially ignorance....lots of great machines made with plain bearings. You want to check deflection (and run out because you are there with an indicator) and listen to it to get some comfort. Do some test grinding and see if you can get a good finish. Not testable? regardless of the paint, you have to for safety discount condition

3) condition condition condition. beater, barely able to stand up: $250, showroom like condition $2500+. Real life, somewhere in between.

JoeLee
12-28-2016, 08:25 AM
Once you have one you'll say how did I ever get along with out one.
If and when you get one you'll find all kinds things to use it for. The quality and accuracy of your projects will improve greatly.
You'll also be able to sharpen all your end mills on it using a simple fixture.

JL...............

MrFluffy
12-28-2016, 08:30 AM
I dont use mine very often (a burdette hydraulic one), but when I do I really needed it for that specific task, and as time goes by I find myself using it more often, and for more diverse things than making stuff flat and a certain thickness which is why I first bought it.

If moving the shop round to fit it in is the level of pain that extra capacity will cost, I say go for it.

bob308
12-28-2016, 09:15 AM
lets see I want to grind a tool bit. I et it up in my toolmakers vice on angle blocks and have it ground up better then even can be done by hand. want to grind something hard and round get out the 5c spin fixture and get it done. put a cup wheel on and use it like a tool grinder. now that is some of the other uses other than just flat work.

yes I would get it if you don't have one.

reggie_obe
12-28-2016, 09:39 AM
3) condition condition condition. beater, barely able to stand up: $250, showroom like condition $2500+. Real life, somewhere in between.

Does it have a magnetic chuck? If no...no sale. Put a cheap import mag chuck on it...no thanks.
Is it under power, can you test grind a few samples and check the finish for problems? If no, risk of bad spindle bearings and possibly, no sale.
Coolant and dust collection are a big plus. Even with both, you don't want to be grinding right next to the unprotected ways of your lathe and mill.

Toolguy
12-28-2016, 09:44 AM
A surface grinder is the Bridgeport of the grinding world. There is so much more you can do than just make straight lines. You can do angled straight lines, angled curved lines, round stuff, grind all kinds of shapes into lathe and mill cutting bits, sharpen end mills , reamers, taps, wheel cutters, carbide tools, make step drills, step pins, gage pins, etc., etc. I would be lost without mine.

Mcgyver
12-28-2016, 09:45 AM
Does it have a magnetic chuck? If no...no sale. Put a cheap import mag chuck on it...no thanks.


agreed.

I have flood coolant on mine, it makes a difference for sure...both in finish and it stops the parts from growing....I'd probably keep looking if not set up for coolant.

Fasttrack
12-28-2016, 10:23 AM
Thanks guys... you've convinced me to at least take the next step and look at this thing.

Any suggestions on what I should be looking for if I can test something in it? Is an eye loupe and a finger enough to test the surface for defects? I used a #2 direct drive model back in college for grinding a few simple parts but really don't have any experience with surface grinders.


(And thanks Mcgyver for helping rationalize my desire for more machines! :) )

MrFluffy
12-28-2016, 10:33 AM
If it has bearing/belt/motor issues, that often/usually manifests itself in the final surface finish on the object, usually visible by the naked eye. Sometimes bad technique produces the same however.
Life is easier with flood cooling, I find its easier not to burn thinner things, keep better dimensional accuracy, cleaner for the rest of the shop too as it tends to damp down the dust when you run a wheel over a diamond or while grinding, but it does make for a disgusting black slime in the sump tanks of the machine to be scooped out. Rather there than on your lathe's ways...

Mcgyver
12-28-2016, 10:55 AM
Like Fluffy said, the smallest problems readily manifest in a visible finish - scallops or other patterns often can't be measured with a tenths indicator but are their for the naked eye to see. With a freshly dressed wheel (standard 40 grit) and a light slow cut you should be able to get a good finish with a machine in good shape. Even the motor not being perfectly balanced (they well balanced motors on quality grinders) will show up in the finish

Perhaps it was here, but I recall a discussion about grinding a test plate to test way condition. I can't recall if the consensus was a its possible or not or what the debate was....but one is unlikely to get that kind of time to check out a machine. A small test should show if there is hope, condition of the ways may have to be by extrapolation of the condition of the rest of the machine.....perhaps someone closer to it can remember the test grind to check ways thing.

Mine came out of a high school as they all shut town their shops. The machines were almost never used and when they were, they were used lightly. (kids think .020 thou DOC is pushing the lathe lol). Especially the grinders that sit there for weeks without being touched - those were the sad days for mankind but the glory days for home shop machine acquisitions :).

Doozer
12-28-2016, 11:46 AM
I liked my 6x12" so much that I have since acquired a 8x 20"
surface grinder. Nice to have.
I have 2 cylindrical grinders and now I am buying a 3rd,
so more is better when it comes to machine
capacity and capability.
I guess I am tooling up to make parts for money
when it comes a time that I can't stand the coorperate
world any longer.

--Doozer

Axkiker
12-28-2016, 12:10 PM
I have 2 (#2's) completely apart in my garage. I pulled them apart to hopefully clean and reassemble. After a several months break due to other projects im really not sure how ill get them back together. I assumed I could find a a detailed schematic to use when reassembling but have been unsuccessful searching. If you run across one please let me know.

Otherwise I might be sol.

OKChipmaker
12-28-2016, 01:21 PM
If you do get it,lift off the table before moving it.The ways can be damaged by moveing it with it on!
I like the roller bearings,dont have to maintain oil in the oil cup,with the chance of damaging them if someone runs it dry.
The ratchet paws that move the table in and out sometimes get worn out and have to be replaced.
Belts are hard to find if it is a belt drive,but there is a work around,if needed.

flylo
12-28-2016, 02:31 PM
I have 3 & have been trying to give away a sng phase 120v 6"x12" with a mag chuck. I think I have a taker but if not (he didn't seem real exited) I'll post it here. It's a Delta Milwaukee & works fine as I used it before I had 3 phase.

Jaakko Fagerlund
12-28-2016, 04:32 PM
Perhaps it was here, but I recall a discussion about grinding a test plate to test way condition. I can't recall if the consensus was a its possible or not or what the debate was....but one is unlikely to get that kind of time to check out a machine. A small test should show if there is hope, condition of the ways may have to be by extrapolation of the condition of the rest of the machine.....perhaps someone closer to it can remember the test grind to check ways thing.
You will also need a surface plate and a test indicator plus that plate you want to test grind and an hour or so of time with the machine to access it closely enough. Grind the plate bot sides, check for flatness on the surface plate. You can't just mic it around, as that only proves parallelism but not the flatness (which is what you want from the machine).

Close enough quick check is to grind several blocks of around 50 x 50 x 50 mm in size from two opposite sides. Quicker than the plate, but you are now relying on a small subset of the ways condition to see what it produces as far as flatness goes. Still you would need surface plate and indicator.

Fasttrack
12-28-2016, 06:30 PM
With a freshly dressed wheel (standard 40 grit) and a light slow cut you should be able to get a good finish with a machine in good shape. Even the motor not being perfectly balanced (they well balanced motors on quality grinders) will show up in the finish
.

Hmm... good point. I don't have a wheel dresser that will work for a surface grinder. Guess I should cobble something up... can it be as simple as a steel block to hold a diamond point dresser more or less perpendicular to the table?

Mcgyver
12-28-2016, 06:37 PM
can it be as simple as a steel block to hold a diamond point dresser more or less perpendicular to the table?

yup....set screw to hold the point. Main reason for dressing is to remove the largest source of imbalance - eccentricity of the wheel periphery that results from arbor to wheel clearance. if the thing is hooked up, the vendor should have a dresser (you'd think). scavenge everything you can with it....you could easily spend more on some of the accoutrements than the grinder (not that you need radius dressers or pin grinders every day, if they are there, try and get them in the deal)

Toolguy
12-28-2016, 06:38 PM
Yes, just use a setscrew to hold the diamond in place. You want to make the hole at about a 15 degree angle though, so you can turn the diamond as it gets a flat worn on it.

Andre3127
12-28-2016, 08:45 PM
If you own a surface grinder, how often does it get used? Constantly

2) Is there anything special to look out for when buying a used surface grinder? Good ways, cable/steel tape table drive if possible, smooth motions on the table, crossfeed and downfeed locks, and a good quiet spindle. Grind a test piece before you buy unless you're willing to send your spindle out for repair. Also, get a 3 phase machine as they tend to give better finishes.


I've used mine for tool and cutter grinding, tool regrinding, everything. It's the handiest tool in my shop, favorite machine, and it brings your level of achievable accuracy up 10x.

After receiving a Shars 2.5" screwless vise for Christmas I've been regrinding it to my specifications. Advertised was .0002" square and parallel....it wasn't even close to that. Some surfaces were .0013" out of parallel. I've now reground over half of it and am within .0001". Keep in mind most Herman Schmidt vises are only rated to .0002".

Some pics:

https://www.instagram.com/p/BOfm97QjGGd/?taken-by=andre_shop3127

https://www.instagram.com/p/BOfozLtD3cO/?taken-by=andre_shop3127

https://www.instagram.com/p/BOgKoCSjN0s/?taken-by=andre_shop3127

https://www.instagram.com/p/BOiMM_2DoME/?taken-by=andre_shop3127

(this is a video of grinding the bottom) https://www.instagram.com/p/BOiZypbjIbq/?taken-by=andre_shop3127

https://www.instagram.com/p/BOk-U-MjrsV/?taken-by=andre_shop3127

https://www.instagram.com/p/BOk_OYGDjHn/?taken-by=andre_shop3127

jbacc
12-29-2016, 05:29 AM
Hmm... good point. I don't have a wheel dresser that will work for a surface grinder. Guess I should cobble something up... can it be as simple as a steel block to hold a diamond point dresser more or less perpendicular to the table?

That is exactly what I use and it works well.

Jaakko Fagerlund
12-29-2016, 08:17 AM
Also, get a 3 phase machine as they tend to give better finishes.
Or if you can't find a 3-phase and end up with a 1-phase, get a VFD that has 1-phase input and 3-phase output. That also gets you adjustable accelerations, so it isn't as harsh a start for the wheel.

One method of checking way flatness I mulled in my head last night which gets you an overall picture of the way wear. Get two dial indicators, both with magnet bases. Set them both on spindle cover or something. Point the first one to the table where the wheel would contact. Move your table so the indicator is in the right end of the table. Now point your other indicator to the middle of the table and zero point indicators. If you now move the table to the other end, any discrepancy between the indicators shows non-flatness of the ways. And watching only one indicator will give you information if the magnetic table has been ground parallel with the ways, which is a requirement for the two indicator check to work.

Jaakko Fagerlund
12-29-2016, 08:19 AM
That is exactly what I use and it works well.
Yup, same here. A piece of hot rolled was drilled & reamed for the diamond point holder at a 15 or so degree angle and a setscrew put in. Then the whole thing was ground and corners broken away so it is smooth all around, easy to wipe clean and doesn't hurt your hands :)

Mcgyver
12-29-2016, 08:44 AM
That also gets you adjustable accelerations, so it isn't as harsh a start for the wheel.
.

This is imo the great reason for a VFD on a surface grinder. The jarring of the wheel on start and stop can move it - there is clearance between the wheel and arbor and they are not torqued down very tightly. The result is you have to (or should) dress everytime you turn it on/off and about defeats the purpose of removable wheel arbors. On big projects, no big deal, but I'll leave the wheel running while changing setups to avoid this (less than perfectly safe) and there are lots of times when i just need something very small done and wish I didn't have to go through the wheel dress thing.

If you are making the decision on how to power but are not yet used to grinding, this is an important consideration. I just acquired a VFD for mine for soft starting/stopping. Unfortunately its a 600V machine so I'll still have the drone of the RPC to keep me company :-(

dian
12-29-2016, 12:37 PM
if its manual you will get to hate it pretty soon. its not easy to check the spindle. a bad grind can be caused by an inappropiate wheel for the test piece, wrong feeds or an inappropriate dress for example, which in turn can be caused by a diamond in bad shape. also the oil can be wrong on flat ways or the ways ruined with balls. if it has a belt that can cause problems also. the "five point method" is useless as has been pointed out.

jaakko, i believe that will not work, imagine two indicators touching the periphery of a wheel.

Andre3127
12-29-2016, 12:45 PM
Or if you can't find a 3-phase and end up with a 1-phase, get a VFD that has 1-phase input and 3-phase output. That also gets you adjustable accelerations, so it isn't as harsh a start for the wheel.



HUH? You can't run a single phase motor on a three phase VFD, and I've never seen a single to three phase VFD rated for more than one horsepower. Some grinders like mitsui's use 1.5HP motors, and you need a VFD rated for higher than the motor if you run an electromagnetic chuck.

I never got on the VFD or ER collet bandwagons.

bborr01
12-29-2016, 01:13 PM
I have a 6 x 12 surface grinder in my shop. It doesn't get used a lot but when I need it I need it. It doesn't take a lot of room and it wasn't very expensive.

Brian

Axkiker
12-29-2016, 01:22 PM
HUH? You can't run a single phase motor on a three phase VFD, and I've never seen a single to three phase VFD rated for more than one horsepower. Some grinders like mitsui's use 1.5HP motors, and you need a VFD rated for higher than the motor if you run an electromagnetic chuck.

I never got on the VFD or ER collet bandwagons.

Here is a link to several single to three phase converters well over 1 hp.

https://cdn.automationdirect.com/static/specs/gs2drive.pdf

dian
12-29-2016, 01:48 PM
this guy apparently has a 10 hp unit:

http://bbs.homeshopmachinist.net/threads/72264-Help-wiring-a-VFD-to-motor

Mcgyver
12-29-2016, 02:00 PM
HUH? You can't run a single phase motor on a three phase VFD, .

He's didn't suggest running a single phase motor on a 3P VFD, he suggested running a 3P motor from a VFD with 1P into the VFD

Jaakko Fagerlund
12-30-2016, 01:34 AM
He's didn't suggest running a single phase motor on a 3P VFD, he suggested running a 3P motor from a VFD with 1P into the VFD
Yup, and there just is no 1-phase motor as it wouldn't turn. The "1-phase" motors are usually just 3-phase motors with a running cap connected parallel with one of the coils to create the necessary phase shift to get rotation. So it is easy to just rip the cap off and connect a 3-phase feed to it and tada, 3-phase motor :)

Jaakko Fagerlund
12-30-2016, 01:40 AM
if its manual you will get to hate it pretty soon. its not easy to check the spindle. a bad grind can be caused by an inappropiate wheel for the test piece, wrong feeds or an inappropriate dress for example, which in turn can be caused by a diamond in bad shape. also the oil can be wrong on flat ways or the ways ruined with balls. if it has a belt that can cause problems also. the "five point method" is useless as has been pointed out.

jaakko, i believe that will not work, imagine two indicators touching the periphery of a wheel.
Ditto on the manual, if you can get power feed, go for it.

You didn't specify where this "five point" (I never said to use points, I said use blocks) has been pointed out to be useless and how.

Also, the two indicator test will work as this is the real world where the table and bed casting ways will NOT wear to a perfect radius match, especially at the ends of the travel where it's not used very much. Most used grinders I've seen show a considerable flatness & thickness deviation in grinding those 5 test blocks just near the outside edges of the working envelope, while the middle one shows as fat.

Andre3127
12-30-2016, 02:32 AM
Here is a link to several single to three phase converters well over 1 hp.

https://cdn.automationdirect.com/static/specs/gs2drive.pdf
Thank you for the correction, I wonder why I've never saw them before? I even (apparently poorly) looked before I went with an American Rotary RPC for my DoAll grinder. Slow starts to start the spindle would be nice over just pulsing the on/off switch a few times.

Sent from my XT1053 using Tapatalk

dian
12-30-2016, 06:42 AM
jaakko, as you said yourself, you need to check the flatness of the work. the five blocks method has to be questioned for the same reason as the two indicator setup. rocking chair effect. before grinding the blocks youd have to grind the chuck anyways, which is not easy.

Doozer
12-30-2016, 08:55 AM
Jaako-
Single phase induction motors are 2 phase.
They use a capacitor to offset the phase 90deg.
They are not 3 phase.
In other news,
a real good reason for a VFD on a grinder
is to be able to change the wheel speed
to change it's hard-soft characteristics
with respect to how it is presented to the
work.

--Doozer

Jaakko Fagerlund
12-30-2016, 12:21 PM
Single phase induction motors are 2 phase.
They use a capacitor to offset the phase 90deg.
They are not 3 phase.
Over the pond has to have some weird motors or different terminology that I'm not aware of, as here you take a 3-phase motor, wire a cap across a winding, config the windings as delta and inject neutral and live (1-phase) over one other winding. Tada, 1-phase motor.
https://upload.wikimedia.org/wikipedia/commons/thumb/9/9f/Steinmetzschema-1.svg/300px-Steinmetzschema-1.svg.png

3-phase wouldn't have that cap, just all three phases connected to the windings in Y or delta config.

Jaakko Fagerlund
12-30-2016, 12:27 PM
jaakko, as you said yourself, you need to check the flatness of the work. the five blocks method has to be questioned for the same reason as the two indicator setup. rocking chair effect. before grinding the blocks youd have to grind the chuck anyways, which is not easy.
Yes, flatness has to be checked, that's what I said originally. If you can't check the flatness of your five blocks, how measuring anything bigger would achieve anything different? And there is no need to grind the chuck for the test, if you are checking flatness of the grind. Of course it helps if you want to grind the blocks from both sides to have them parallel and that way measure them more "easily", though that is supplying a point of error as you are actually measuring parallelism and not flatness.

As this question arose of the rocking chair effect and theory vs real world, I might go and check the grinders at work later today and see if I can get some measurements. All I know is that they will show differing measurements with two indicators, as both of them grind differently at the ends of the travel than in the middle (about 0.02 mm difference with large plate). So this already confirms that it hasn't worn to be an equal huge radius that the two indicators wouldn't show.

dian
12-30-2016, 03:25 PM
not sure what you are saying. flatness of the blocks? you check their height, right? or are you somehow going to put the granite on the grinder and blue them up? if the grinder is perfect and the chuck is not, then the blocks will not be equal.

Andre3127
12-30-2016, 07:40 PM
Single phase is different than two phase, look at sine wave charts. A two phase motor, common during the early 20th century and actually found on a few Bridgeport's from the factory cannot be run on single phase power.

Sent from my XT1053 using Tapatalk

Jaakko Fagerlund
12-30-2016, 07:48 PM
not sure what you are saying. flatness of the blocks? you check their height, right? or are you somehow going to put the granite on the grinder and blue them up? if the grinder is perfect and the chuck is not, then the blocks will not be equal.
No, check the flatness of what you grind. The height of the blocks doesn't matter if you are only interested in measuring flatness of one surface. Basic measuring job on a surface plate.

Sparky_NY
12-30-2016, 08:22 PM
Jaako-
Single phase induction motors are 2 phase.
They use a capacitor to offset the phase 90deg.
They are not 3 phase.
In other news,
a real good reason for a VFD on a grinder
is to be able to change the wheel speed
to change it's hard-soft characteristics
with respect to how it is presented to the
work.

--Doozer

Can you explain that hard/soft you speak of by varying the speed? I have a boyar schultz 6x12 with a vfd. I have it set for about 10 seconds acceleration and the same on decel. Being a novice at grinding, I wondered if there might be a use/reason to slow the wheel down for any reason. I don't have a clue.

dian
12-31-2016, 12:29 PM
a fast wheel acts harder and vice versa.

eeler1
12-31-2016, 01:10 PM
Next best thing to having a surface grinder is to have a friend that has one. You could be that friend.