Author Topic: Tool Grinder  (Read 17402 times)

Offline Darren

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Tool Grinder
« on: December 27, 2008, 07:31:32 AM »
One way of doing it I suppose !!

You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)

bogstandard

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Re: Tool Grinder
« Reply #1 on: December 27, 2008, 08:10:07 AM »
Hi Darren,

Very rough and ready, but if it works, 'nuf said.

Bit difficult doing internal grinding though, and I think the peripheral speed might be a bit high, lots of heat generated.

John

Offline Bernd

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Re: Tool Grinder
« Reply #2 on: December 27, 2008, 10:54:03 AM »
I'd probably tip my lathe over if I mounted the grinder I have like that.  :)

But it gives the brain something to think about if I ever find a samller version.

Bernd
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bogstandard

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Re: Tool Grinder
« Reply #3 on: December 27, 2008, 11:30:34 AM »
I forgot to add, in that configuration, the chuck needs to run backwards. Much too much friction and burning otherwise.

John

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Re: Tool Grinder
« Reply #4 on: December 27, 2008, 06:11:34 PM »
OK newbie time again.
I like that idea but the thought of all that grit flinging
around in close proximity to h/s bearing and chuck
scrolls gives me the willies. Your thoughts gentlemen!
BR.

PS How about mounting the grinder on a vertical slide
to make a surface grinder? Feel free to shoot me down.

bogstandard

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Re: Tool Grinder
« Reply #5 on: December 27, 2008, 08:13:37 PM »
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
« Last Edit: January 19, 2009, 02:45:08 PM by bogstandard »

Offline Darren

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Re: Tool Grinder
« Reply #6 on: December 28, 2008, 02:05:04 AM »
BR,

In fact what Darren is doing is dicing with a nasty accident waiting to happen.

John

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
« Last Edit: December 28, 2008, 02:06:37 AM by Darren »
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bogstandard

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Re: Tool Grinder
« Reply #7 on: December 28, 2008, 05:36:27 AM »
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

Offline Darren

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Re: Tool Grinder
« Reply #8 on: December 28, 2008, 06:40:13 AM »
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
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Offline sbwhart

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Re: Tool Grinder
« Reply #9 on: December 28, 2008, 06:59:52 AM »
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:

A little bit of clearance never got in the road
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Location:- Crewe Cheshire

bogstandard

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Re: Tool Grinder
« Reply #10 on: December 28, 2008, 08:03:49 AM »
Darren,

Only prob with the die grinder is as you mentioned, it blows the grinding dust everywhere. Maybe a little shroud around it to direct the blast away from the grind area would be a prudent thing to do.

I have bought a cheapo die grinder, but not for grinding. I need a 50K+ motor to make a precision drill press.

The recommended speed for the drills I want to use is 96K, so I will just up the pulley size a bit, to get it closer to the range I want. Not worried about the noise aspect either, as the operation should be completed in a couple of seconds.

John

Baldrocker

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Re: Tool Grinder
« Reply #11 on: December 28, 2008, 06:36:56 PM »
Jeez  I only arst.
But then maybe the responses saved me a nasty
so all well and good
BR

bogstandard

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Re: Tool Grinder
« Reply #12 on: December 29, 2008, 03:18:45 AM »
BR,

Not shooting you down in flames, just making someone realise that there is usually a little bit more to something than what is seen.

If things are done in a safe and calculated manner, all sorts of things become available, but diving in with eyes closed can lead to serious problems.

There was once an article in one of the modelling mags (don't ask, I have given most of them away) about making and using a bench grinder as a swing surface grinder, and it worked very well, and in a safe manner.

Attached crap-o-cad gives the idea.

John

bogstandard

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Re: Tool Grinder
« Reply #13 on: December 29, 2008, 07:59:08 AM »
That's great Ian, I must still have that article in my collection, as MEW are the ones I never got rid of.

John

Offline SPiN Racing

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Re: Tool Grinder
« Reply #14 on: January 01, 2009, 11:19:42 PM »
NOOB TIME


Ok... so I have been building and racing Rotary powered cars for many many years. I have built my share of engines, and all of them (knock on wood) are still ripping along strongly.
My work on them has been from instruction I got from the old school masters.. (I know a couple guys who have been building them for years, one of which is quite infamous as having help buid the engines for the LeMans cars.)
Needless to say.. a lot of information I went with and extrapolated the theories, and the reasoning, combined with my aviation knowledge, and slew of other random knowledge.. and have ended up with some very nice engine designs that work very well.
By designs I simply mean, porting designs, and or modifications within rule sets, to generate additional power over what was conventionally considered the hard limits.

All this being said.

I know that when someone has a rotary engine they can have it... "machined" in a manner that I BELIEVE is called Blanchard Grinding? Basically you bolt the steel end plate, or center plate of the engine... that is perfectly flat, to a machine.. and it has a VERY LARGE DIAMETER stone, that exerts a goodly amount of pressure... generates a massive amount of dust.. and makes the surface VERY flat. Like 4 decimal places I think? And mirror smooth?  Only a few shops in the USA in the rotary "world" are capable of having this done.

SO I understand that form of grinding..

Why would you use a stone to grind a shaft, or somethig in a lathe?

I mean... Im trying to figure out the specific use of a grinding wheel on a lathe.

I wouldnt think it was to remove a "lot" of metal would it? Doesnt seem like it would be very precise.
Is it for a specific level of finish? If so why not polish it?

Sorry for the noob question.. but I was trying to understand why.

Scott, scratching his head
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Offline Darren

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Re: Tool Grinder
« Reply #15 on: January 02, 2009, 04:16:58 AM »
Hi Scott,

I'm certainly no expert on lathe grinding having never done it as yet. So others will join in and add their slant on this issue hopefully.

From what I understand grinding a shaft or say an internal taper on a lathe will achieve a higher degree of accuracy than normal lathe tools.

Polishing may make an item nice and smooth, but it ruins accuracy.

Also grinding may be the only way to work a really hard material. Perhaps just to remove the outer hardness on a tool or shaft. Then normal machining can presume.

Darren
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)

bogstandard

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Re: Tool Grinder
« Reply #16 on: January 02, 2009, 04:26:23 AM »
Scott,

Just to enlarge slightly on what Darren has said.

You are perfectly right to ask the question, and you have answered most of the question in your assumptions.

Like in the full size engine department, you wouldn't turn a camshaft or crank, basically they are too hard, so they have the journals and lobes ground. Because only very minor amounts are removed, the surface gets a very smooth and highly accurate finish (as long as the stones are dressed in the correct manner).

The pic I showed of internal grinding. That was being done to true up the collet chuck that I had fitted to the lathe, and needs to be super accurate to carry out precision turning. By grinding the hard nose where the collet fits, I achieved a 0 - 0 runout on it.

So say you wanted to make a one piece crank for an engine, you would rough machine the crank, leaving the journals slightly oversize. Then after the crank was hardened, you would grind the journals down to the required size. In your field, you could get worn journals on a crank reground, then fit undersized bearing shells.

The same goes for surface grinding, you can achieve perfectly flat, very accurate, highly smooth finishes on almost any material, including ones that you couldn't machine with normal tooling, ie solid carbide, rubber etc. You could also grind those materials on a lathe, if you needed a round profile.

So really, grinding is a specialist machinist job, whereas other trades have turners, fitters and mill operators, people are employed just as grinders.

BTW your accurate drill rod (silver steel) is ground stock, to achieve the accuracy required.

I hope this has made it a lot clearer for you.

John


Offline SPiN Racing

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Re: Tool Grinder
« Reply #17 on: January 02, 2009, 01:35:47 PM »
VERY much clearer!!

I had always heard the term referring to a different grind on a cam.. or re-grind a cam.. or re-grind a crank.
I never really put the 2 and 2 together to figure that out.

In my experience the only grinding I ever saw done around the house, was my dad with a bench grinder, sharpening lawnmower blades, and or chisels. ANd the grinding wheel was pretty rough.

In the race shop I do weekend work at.. they have a green wheel they use on one side of a grinder, and a wire wheel on the other. The shop owner will clean up the tip of a HSS or supposedly carbide bit.

I ended up buing a Carbide green wheel sharpener from Sears. It was around 60 bucks or so, turns slowly, and runs the wheel through a water bath. I have re-sharpened and changed the profile of some of the tools I have. But its not what were talking about here.


<taps chin>
Very interesting.

SO. THis beign the case..
My future project I want to build skills to be able to do. A Mini working Wankel engine, modeled after the Mazda rotary. Im thinking 1/4 scale off the top of my head. I am going to have to seriously think on my tooling, and procedures.
I know the Epitrochoid shape of the combustion chamber/rotor housing.. takes special work to machine. (Hourglass shaped housing) And the eccentric shaft.. aka crank shaft. shouldnt be too hard to replicate.. BUT.. I think it will be something that requires proper grinding.

<Adds info to the corner closet in the brain on things to compile info on>
SPiN Racing

Offline sbwhart

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Re: Tool Grinder
« Reply #18 on: January 02, 2009, 04:23:32 PM »
Hi Scott

I may be able to down load a bit of info for your memory banks, for when you start on your model wankel engine.

Below is a photo of a UK 50p  that has the same caracteristics to a wankel cylinder ie constant dia



How can this help you may be thinking, well a long ltime ago, when I had hair, I used to make the tooling for blanking these coins out (all within the law I may add). They were made on a specialist grinding machine for grinding taps, good quality ground taps have a radialy releafed form, in simple terms the grinding wheel goes in and out in sincronation with the rotary movemet of the tap. To grind the tools for the 50p we simply had a special cam made so that the wheel went in and out and generated the coin shape in the tool. The make of the grinder that did this was a MATRIX Coventry Thread Grinder, a compy that, like much of British Industry is No longer in buisnes but I'm shure that if you do a google search you will find some information.

I can also remember reading an article in Model Engineer about a modler that made/adapted a cylindrical grinding machine for grinding cams for model petrol engines he used a full sized cam as a master and by some cleaver mechanism scaled the movement down to produce a model cam, as I've only been reading ME for the last five years it is quite a recent article, but I can't remember  :hammer: exactly when

I hope this info will be of some help to you

Have
 :wave:
Fun

Stew
A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline Divided he ad

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Re: Tool Grinder
« Reply #19 on: January 02, 2009, 04:37:22 PM »
Did someone say miniature working wankel engine??!?!


How about this as a starter from last years Harrogate show..... Sorry you'll have to turn through 90' for one... I'll change it someday!











Hope these inspire?



Ralph.
I know what I know and need to know more!!!

Offline SPiN Racing

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Re: Tool Grinder
« Reply #20 on: January 02, 2009, 06:48:06 PM »
OMG!!!!

I sooo want those.


Actually I have some key chains and avariety of Rotor shaped items.

But those engines are very very sweet.
Im quite impressed.
My best friend who is the Rotorhead who got me started back in 1988 is here looking over my shoulder.. and were both laughing.. and impressed.

MORE for the brain to process.

BTW.. OS Engines in Japan makes a Rotary R/C Aircraft engine as well. And it is classified as a .30 Cu In engine. One rotor.
I considered buying a couple of those rotors and making a 2 rotor. Or 3? Or 4?

SPiN Racing

Offline Bernd

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Re: Tool Grinder
« Reply #21 on: January 03, 2009, 10:53:53 AM »
Spin,

Here's a bit more info for your brain to absorb. The company I used to work for Gleason Works holds the original patent on the machines that cut and grind both the cylinder(?) and the rotor.

To bad the wankel never succeeded as a power plant for cars.

I was also going to mention that a wankel engine was available for the model airplanes. Also I believe there are/were some snowmobiles that are wankel powered.

Bernd
Route of the Black Diamonds

Offline SPiN Racing

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Re: Tool Grinder
« Reply #22 on: January 06, 2009, 07:07:52 AM »
To bad the wankel never succeeded as a power plant for cars.

He he
Um
Mazda has had a rotary powered car or two, available since I believe 1968? Or 69. Starting with the R100, RX2, RX3, RX4, RX-5 Or 1st generation Cosmo, The REPU Rotary Pickup that Furd based the Courier on, the RX6 never appeared. The 1st, 2nd, and third generations of RX7 from 1978-1997(92-97 I think.. was only Japan and AU.. thanks Furd). The 2nd Generation of Cosmo late 80s to early 90s with a 3 rotor twin turbo, and the current Model the RX8.

In addition there are several snowmobiles with rotaries.
Suzuki had a rotary powered motorcycle for many years in the 70s.
SOme Russian company made rotary cars that were crap.

Osaki engines makes a small RC aircraft engine that is 1 rotor, and .30CU in.

There is a new karting company out there making a One rotor engine for karts, that I gather is tearing up the field.

There was a British car company that made rotary powered cars.. but Im mentally stumped atm on teh name.. but they were a flop. They were peripherally ported, so the powerband was up around 6-8K. ANd the Rotor seal technology wasnt so good back then, so they failed a LOT. Also the engine made negligible power down low, so you needed to rev the you know what out of it to get it to perform... and this was the day of the 900CC MG engines.

Also one last snippet..
Mazda, with a 4 rotor engine is the only non European manufacturer to ever win LeMans 24 hours. The car.. the 787B.


Oh yeah.. Im a bit of a Mazda rotary nerd.
I went to North Carolina from Florida one time for a Mazda gathering. At the time I had 12 RX-7s all in perfect working order at the house. Won a T-Shirt from Mazda North america for having the most running mazdas.
 :lol:
SPiN Racing

Offline Darren

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Re: Tool Grinder
« Reply #23 on: January 06, 2009, 08:16:20 AM »
And Don't forget Norton in the 80's, floored the track with em they did.... :clap:
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Offline HS93

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Re: Tool Grinder
« Reply #24 on: January 12, 2009, 03:57:01 AM »
This may interest a few on hear sory it is off topic but it follows on from previouse posts. I found it interesting, there is plenty on the site to look at, good considering its a small company


http://www.parajet.com/

http://www.parajet.com/index.php?id=122

http://www.skycarexpedition.com/

Peter
I am usless at metalwork, Oh and cannot spell either . failure