Surface Grinder Ripples

[metalmagpie]

I found what may be the above-mentioned document:
http://vintagemachinery.org/pubs/detail.aspx?id=6564

Thank you for mentioning this document! It's the best thing I've seen on how to run a surface grinder.

 

[Zap921]

Here it is in pdf on Vintage Machinery: http://vintagemachinery.org/pubs/256/6564.pdf

 

[Zap921]

I'm too slow, good job metalmagpie!

 

[michiganbuck]

I think dressing the wheel was the main reason for the better finish.
Very often the long travel feed that feels comfortable at hand cranking on better quality grinders proves better than crazy fast or crazy slow. I usually try to target that speed with a power feed.
I believe incremental crossing with too big of increments can cause sporadic wheel slow down and cause messing up the surface finish.
*It is not uncommon that .020 to .050 straight across cross-feed increments will give the best finishes on a warmed-up surface grinder having a fresh dress, or lightly used after dress with the take being .0003 to, 005 and wet or dry with having a decent over travel at the ends of long travel so to avoid heat build-up.
Down grinding usually achieves the fastest stock removal, and incremental cross grinding usually produces the best surface finish. Often a combination of these two technics produces the best productivity.
*Here is a video about surface finish all new grinder hands should see ( 8:44, 21:10, and 26:30 ) to end are very interesting. *But don't skip ahead because the whole video (about a half-hour long) is good to the very end.

 

[eKretz]

I think he dressed the wheel and maybe moved the table back and forth a little faster. Both of those would have been my starting point based on what the surface looked like. That plays back to wheel selection. If the wheel is a little on the too-hard side, gotta keep the table moving fast and/or slow down the spindle a bit. If the wheel on the other hand is on the too-soft side it's better to slow the table down and/or speed the spindle RPM up. All of this stuff ties in together in a bit of a give and take.

 

[4GSR]

Cimcool? i haven't seen that stuff around in over 30 years!!! There are much better stuff out there to use in the way of coolant now days. Radiac wheels are all I use on my little SG, B & S 612, they haven't let me down yet! I get lazy and don't keep the wheel dressed as I should at times but it does good.

 

[michiganbuck]

Cimcool? i haven't seen that stuff around in over 30 years!!! There are much better stuff out there to use in the way of coolant now days. Radiac wheels are all I use on my little SG, B & S 612, they haven't let me down yet! I get lazy and don't keep the wheel dressed as I should at times but it does good.

if that is the blue Ice we used back in the 60S?
I was smoking cigarettes then and that coolant would make a cigarette taste like Cotton Candy ..Uck.

 

[michiganbuck]

Before walking away from this thread congrats on the much better finish. The photo in post 15 is much improved, but most customers would not like the streaking and bouncing
Likely the only way for the guys here to help you get the best finish your machine can make is by your telling the wheel material, grit size, wheel hardness and the part hardness along with your technic.

likely too much cross travel with using the Proth feature of criss-cross travel, and possibly wheel follow edge wobble. But no point in guessing with not enough facts.

 

[Richard King]

if that is the blue Ice we used back in the 60S?
I was smoking cigarettes then and that coolant would make a cigarette taste like Cotton Candy ..Uck.

I sold my shop machines heck 20+ years ago. I got 2 of my guys jobs at Kurt mfg, one went to Graco and eventually ended up at Kurt and my Foreman Craig Laurich started to rebuild machines out of Buhl, MN . I sold the grinder and my planner to Rick at A&D Machine Rebuilding in Roberts WI. If you go to his web-site my old 8' Brown & Sharp is hanging on his hoist. Also he has a set of King-Way Straight Edges on his surface plate. Those were shipped to Jan Swerre Haugjord in Norway. Look on Pictures - https://www.admachinerebuilding.com/

 

[Toolmaker51]

I found what may be the above-mentioned document:
http://vintagemachinery.org/pubs/detail.aspx?id=6564

Thank you for mentioning this document! It's the best thing I've seen on how to run a surface grinder.

Agreed; contrary to a textbook, this by a manufacturer is more hands-on than a "yeah, I know how" author.

 

[jccaclimber]

I’m going to make a few assumptions based on your past threads, if they are incorrect please don’t take offense.
1. I’m assuming this grinder is part of the warehouse full of “collected” machines you posted previously, and is in somewhat unknown and likely imperfect condition.
2. I’m going to assume you’re fishing in the dark, not working in person with an experienced grind hand (which I’m not). When you say it’s done good work before is that your personal experience, or what the guy who sold the old machine to your buddy told them?

Not trying to pass judgement, just determining if it’s a recent change or something that’s been there a while. You’re in the right place regardless.

1. Make sure the machine has all feet uniformly loading the floor. Properly leveled is good, but at least not rocking around like a bowl feeder is a sufficient start.
2. Dress, and ideally balance the re-dress the wheel. If you aren’t equipped to balance the wheel just dressing and properly securing it is fine. Forgive me if this is too basic, but make sure the paper wheel blotters are still there, and larger than the mounting flange. They are important in preventing the wheel from exploding.
3. Compare warming up the spindle for a while, dressing the wheel, then grinding a part without shutting the spindle off to grinding without a fresh dress and warmup. On a new machine with good spindle bearings the dress leftover from the last guy is often fine. On an older somewhat worn machine you may find you need to do a quick whee dress any time the spindle has been stopped and restarted, even if only for 30 seconds.

Hopefully the bottom of that part is flat so that it’s sitting securely on the chuck?

 

[michiganbuck]

I have never used a Proth but it seems a good grinder out of Taiwan.
One feature it has is crisscross travel so there is cross-feed and long travel at the same time while grinding the part.. I believe this crisscross travel is detrimental to surface finish because it impacts an additional force, being a push to the side or cross direction of the wheel. The clearance needed for down travel, and the natural state of the wheel head is/can be jeopardized by any side pressure.
Often a surface grinder will have a favored direction of cross pressure to the wheel. A guy/gal who really wants to know the grinder will try to dress and grind in both cross directions* to see if there is a slight improvement in one cross direction over the other. (some grinder hands may do this for roughing only.)

*both cross directions in the individual grind is not good.
Cross-feed one way after dressing, and only cross again after going back to the original start side/edge...if you dress again or not.
(X) crossing feeding back and forth after a dress on a part is a poor way to grind for the best surface finish or size.


*For the Op: Justin, take three .001 dresses (or clean up the total wheel bottom) and stick the wheel with a piece of wood, then grind the part with straight across cross feeds (not crisis cross) to take .002 off the part with your cross increments being .020..and have 1" over travel at the ends of long travel.

Then dress again and make the same .002 grind, *but start the grind at the rear to increment outgoing (opposite cross travel).
Make your long travel at a speed that would be/seem a comfortable hand-cranking speed.
Post both photos if they are notably different, or just one photo if they are the same.
Buck

 

[eKretz]

I noticed that weird travel when I saw the grind marks at an angle to the edge... Thought he had just set the part on the chuck at an angle! I don't care for that either. And yep, dressing in only one particular direction for finishing does sometimes work better on certain machines.

 

[michiganbuck]

Re: if the side pressure changes the wheel pitch .000010 you might see some wheel edge marking in the surface finish, may be too small to measure but may be visual..
Also, it can make the following wheel edge wobble mark the part..good to bump the follow wheel edge with a hand angle dress when doing super surface finishing..

the state of the wheel head can be found by setting an indicator to the wheel head and giving a hand push in both cross directions(in and out).
The direction that indicated the firmest/least slop is likely the best cross-travel to use for optimum surface finish.
Push with the number of fingers..about 7 to 10 lbs per for most guys.

Big step-overs can load up and dull the whole wheel so there is no finisher-portion of the wheel bottom.
I had jobs that needed fresh clean water to make finish spec.

 

[michiganbuck]

-Justin,
You do such a great job of taking photos that you could do a service to the abrasive threads if you would deliberately grind samples of poor and good grinds to initiate a thread on various grinding problems.
I copied your latest photos.
I would like you to make perfect that latest part, with positing a photo..and do a photo of a hard surface burn. run it dry with too much take-off stock (agree that may ruin a good piece of steel that would need straightening.)
Buck

 

[DrHook]

I think dressing the wheel was the main reason for the better finish.
Very often the long travel feed that feels comfortable at hand cranking on better quality grinders proves better than crazy fast or crazy slow. I usually try to target that speed with a power feed.
I believe incremental crossing with too big of increments can cause sporadic wheel slow down and cause messing up the surface finish.
*It is not uncommon that .020 to .050 straight across cross-feed increments will give the best finishes on a warmed-up surface grinder having a fresh dress, or lightly used after dress with the take being .0003 to, 005 and wet or dry with having a decent over travel at the ends of long travel so to avoid heat build-up.
Down grinding usually achieves the fastest stock removal, and incremental cross grinding usually produces the best surface finish. Often a combination of these two technics produces the best productivity.
*Here is a video about surface finish all new grinder hands should see ( 8:44, 21:10, and 26:30 ) to end are very interesting. *But don't skip ahead because the whole video (about a half-hour long) is good to the very end.

Curious what you mean when you say "down grinding"...

 

[michiganbuck]

Curious what you mean when you say "down grinding".. -Incremental cross-feed grinding: grinding with a set down feed amount to take from the part and then crossing over the part with incremental step-overs using the cross-feed, and long travel. -Down Grinding: grinding with the wheel stationed over the part and using incremental down-feed travel, along with long travel movements to grind the part. The OD of the wheel is the strongest application of forces to the part. loading does impact the entire wheel bottom so after a time the surface finish quality can be reduced. *OH, I should add that down grinding can push the part along the magnetic chuck, so a block-in device needs to be put in front of the Go Direction of the part. Go Direction: where the part would go if set free from all holding, Often when much stock needs to be removed down grinding is by far the fastest, and then a dress skim if needed for surface finish specification and an intermittent cross pass. This does need sufficient hores power, perhaps 3/4 hp and up. With the likes of a 46 grit wheel this same wheel can be used.

 

[eKretz]

Curious what you mean when you say "down grinding"...

He means no in or out (cross feed) table movement, just heavy grinding downward in one place. Then lift the head back up, move over and do it again. Then lift the head back up, move over and do it again. So on and so forth. It's about the fastest way of stock removal on a reciprocating horizontal spindle surface grinder.

Edit: looks like Buck replied while I was typing. And as usual, in a way more thorough manner!

I'm a little less wordy, Buck is the man.

 

[DrHook]

Those sort of answers are why I come here...

 

[richard newman]

I'm a little confused about the terms being used - "long travel" is side to side, as in reciprocating, yes? And cross feed is in (or out), for the stepovers?