Gallery, Projects and General > Neat Stuff
Tool Grinder
bogstandard:
BR,
Really with a standard sized TP grinder, there is not a lot to worry about. It all depends how messy you work.
I normally cover the area in cloths to protect the bedways, and only when I am dressing the stone and truing it up with the slides do I cover everything up, but of course the lathe is not running under those circumstances, just the grinder.
This is doing internal grinding, doing the initial truing up of my collet chuck. The chuck is running in reverse and the stone is running in the same direction. For external grinding, the stone will turn the same way as this one is doing, but the chuck will be running in it's normal forwards direction. The stone should really always go against the direction of chuck rotation, not with it. You also usually use a faster speed for internal grinding, slower for external. You can use suds for keeping the dust down and prevent burning, but I never go to the extremes that require that sort of action.
Stones for this sort of grinding are specially made to do the job, as are surface grinding stones, so really the general purpose offhand grindstones are not ideal.
Your idea about using a vertical slide for grinding could be done, but I personally would advise against it. Grinding is one of the most dangerous machining exercises you can do, and playing about with it is not a matter to be taken lightly. It is very easy to make a stone explode. In fact what Darren is doing is dicing with a nasty accident waiting to happen.
John
Darren:
--- Quote from: bogstandard on December 27, 2008, 08:13:37 PM ---BR,
In fact what Darren is doing is dicing with a nasty accident waiting to happen.
John
--- End quote ---
Er. scuse me, :wave:
I'm not doing anything of the sort. That's not my bench grinder parked on the slideways in that picture.
Official description of this section of the forum reads "Didn't make it but have pictures or videos of inspiring things? Found on the interweb? "
My set-up uses an air die grinder, I say my set-up I've only just done it a few days ago but had no time to post about it.
I'll try to put some pic's up later... :D
bogstandard:
Sorry about that Darren, but when I log on, I just go to unread posts and it bypasses all the main headings and it came over as it was something you were doing.
In fact it was the instability issues of such a large lump being carried on a lashed up toolpost that had me worried. It would only take one jolt and due to vibration, that stone would be bouncing around trying to take a 50 thou cut in one go with dire consequences.
John S had a similar setup shown on his old pics about machining a piston, but if you look at his setup, it is mounted rigidly onto the cross slide, and so is deemed safe to operate. You can't see the mounting of mine very well, it replaces the whole toolpost, and is very rigid, and I only use a max wheel size of 2.5" x 1/4" wide, not 6" x 1/2" wide.
I am no super expert on grinding because I don't do it for a living, but I have done many hundreds of hours both surface and toolpost grinding in a prototyping environment. Because of that, I had to attend, every two years, specialist grinding seminars, lasting for nearly a week each time. That was all because part of my job was to mount and dismount stones on on a range of different types of grinders.
If you had to attend such a seminar, people would soon realise that when we are sticking any old grinding crap together, we could be taking our own lives in our hands. Hence the red rag to a bull episode and my warnings about grinding.
With reference to your die grinder, fine, but keep an eye on stone speeds, mine is limited on my toolpost grinder to 18,000 max, well within the normal allowable speed range for mounted points. A die grinder just might be able to exceed the speed limits of certain stones, especially external grinding wheels. People seem to think that just because they can buy the equipment and stones, they are safe to use. Far from it, manufacturers will sell you anything if it gets their profits up, they are not worried if you hurt yourself by using it improperly. I paid less than 10 pounds for my air die grinder, but before I put a stone anywhere near it, I will make sure I have all the facts first.
For other people who use clone mini drills that only have plain bearing supports for the collet, they are asking for trouble. A stone has to be presented to the work in a very rigid manner, and maintained that way during the whole course of grinding. It only takes a minor slip up and that stone will dig in and be liable to shatter at the speed of light if it isn't supported rigidly enough.
Dressing is another major issue. Stones are moulded, and as such are unstable to be used until properly dressed and trued, plus in the case of most surface grinding, balanced as well.
So along comes a totally oblivious model engineer, most probably running the stone way over it's safe operating speed, wobbling all over the place because of being both unbalanced and not dressed and trued up, getting crappy results all because he doesn't know what he is doing, and decides to 'give it a bit more' and hope it cleans the job up. A sure recipe for disaster. Stone shaped hole in the middle of forehead.
Before anyone pipes in that it is not that dangerous, and it will never happen to them, I suggest that you book into a grinding seminar, and they will show you pictures of people who thought they were 'above the law'.
I am not pointing a finger at anyone over this issue, because we all know better, don't we?
Let's be careful out there.
John
Darren:
Hi Guys... :wave:
What a reaction, wow....but that's great, sorta what I expected from that picture.
On the other hand my apologies. I was just on my way out to a "buffet" when I saw that pic and knew if I didn't post it right then I would forget all about it later.
The comment "One way of doing it I suppose !!" was intended to be flippant, extenuated with the use of double exclamation marks.
But yes I should have written more at the time to further clarify..
In a way I'm glad I didn't, so much good information enstrewed by the time I got back to read the replies :headbang:
I bought my die grinder some years ago for porting and gas flowing the cylinder head on my bike, after destroying not one but two flexileads and drills trying to do the job.
The air grinder was great, kept cool during some hard work, the flowing air, (flexi lead got incredibly hot) blew the dust away from the work and it lasted out to finish the job. In fact later I then did a 16 valve car head and I still have the air grinder in perfect working condition...brill.
Not used it now for many years, but I was looking at some scrap on the bench and thought.....I wonder...!!
More to come... :D
sbwhart:
hi Chaps
Its a very healthy reaction to warn each other of potencial dangers, I've worked all my life in an industry that has some dodgy materials and processes and we have it drummed into us that we have a:- duty of care:- to both ourselves and to others, people are activly encourage to chalenge each over if they see any unsafe activity.
top marks
As for grinding wheels just a few golden rules
1:- Check the speed rating of the wheel
2:- Mount it correctly ie washer of even diameter etc don't try a bodge.
3:- Check the wheel for cracks by giving it a light tap, dull ring its cracked:- try it on a cracked cup.
4:- Always use the little paper washers suplied with the wheel steel to whell clamping will lead to desaster
Have Fun
Stew
:wave:
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