Tool and Cutter Grinders.

I keep looking at T & C grinders and keep asking myself how can I justify spending hundreds of £'s acquiring a machine. Especially when considering how cheap milling cutters are these days. You can buy a lot of cutters for what you would pay for a T & C grinding machine. Other than the pleasure of regrinding them, I don't seem to be able to justify the expenditure. What do others think.

Alan.

I suppose the high costs (vertex make a "reasonably" priced one brand new) are probably due to their mechanical complexity, lots of moving precision slides and the fact that they remain popular among their devotees who will accept the expense in order to reap the luxury of owning one.

I suppose it's one of those things where you don't really appreciate them until you use them. I would say if you have alot of tools to resharpen and form complex accurate angles onto milling cutters and form tools, then you can justify it. If you only want to resharpen lathe knife tools, forget it and focus on making a precision tool rest instead if you want more accuracy and sophisication out of a bench grinder. 

Michael W

Edited By Michael Walters on 26/10/2016 19:29:11

Hi Alan,

Buying a commercial T & C grinder is expensive, outside my limited budget. If you find a proper T & C grinder is too expensive, may be Harold Hall's Grinding Rest and accessories might full fill your grinding needs? As long as you don't mind making one.

Thor

Yes of course cost will always be an issue. I did make Harold Hall's simple grinding rest, not the more complex version. I have used it with a degree of success to regrind some end mill cutters using a bench grinder which sparked my interest in buying something more sophisticated. Either a second hand or new T & C grinder. Second hand Clarkson T & C grinders are reasonably priced but all the ones I have looked at lately don't come with all of the necessary tooling. So further cost's would be incurred.

Alan

One of my first projects was a Worden T&C grinder, it's an expensive kit but I have never regretted building it. I'm now most of the way through building a Quorn, just because the castings came along at a silly price, it will incorporate a lot of modifications from the original design and has taken a while to build, mainly because I'm doing it alongside building 2 traction engines but, again, no regrets in building it. The Worden gets used most times I am in the machine shop and I'm sure the Quorn will be the same. Not sure I would be looking at Clarksons, as you have pointed out, many of them lack the additional accessories.

If you can't justify the expense of a dedicated T&C grinder, another option is the Acute jig from Eccentric engineering. It looks a good design and is not overly complex or as expensive as a Worden or Quorn

Hi Graeme, I looked at the Acute system when I visited the Doncaster exhibition but at the time not overly impressed with it. Regarding the Worden, Deckel and Quorn, they are fairly rare and when you find one there is a lot of interest and they go for silly money. I did recently bid on a Stent but lost out. I also think that the Quorn is not sufficiently rigid (I may be wrong with my perception as I have had no experience with them) hence the interest in the Clarkson which I feel is a more robust bit of kit. I would love to justify the expenditure for a Vertex version, even if I had to buy a Chinese version. But around £700 including shipping!!! Or a Warco version at £525 but you need to spend a lot more for the attachments to be able to use the equipment.

Alan.

The Acute grinder sharpens end mills without a problem. I use a Harold Hall rest I made for shaping lathe tools.

I made mine from stock metal so didnt cost too much either.

Both use the same standard grinder I can change between the two in minutes.

I've always felt the tool and cutter grinder folk, both hobby and professional, are over impressed with infinite set-up, do any angle and any shape capabilities. Reckon that a few accurately pre-set angles would do for a wide range of use. Certainly should be possible to cover the needs of most Model Engineers and Home Workshop types. I have a Clarkson about the place and casual setting up for most purposes is insanely difficult. About the only really easy thing is the drill sharpener. Which I don't use!

Somewhere in the pile of back of envelope sketches I have most of a design for a stack up tool carrier system using different sized rods slid into Vee grooves between hinged plates to set the angles. If I ever finish it it will sit on the Clarkson table to get the traverse across the wheel motion. Would need a simple sliding base to use with a normal grinder fitted with a cup wheel. Not difficult. Naturally it has robust gauging system to set the baseline tool projection with sensitive adjustment "click-click-click" style to control the amount ground off. For 4 facet drill sharpening it has a shake free pivot left and right angle stops so the primary clearance is ground going one way and the secondary coming back. Proper position gauge and 180° investable carrier of course.

So why haven't I made it. Simples. Can't figure a good method to generate properly defined radii on lathe tool tips. I can manage with what I have. If I'm gonna build something its got to work. Properly. That means no more than 5 minutes to re-configure if its not already basically set for the tool type to be sharpened and no more than a minute per edge to be sharpened. That said I figure taking more than minute for a drill is pushing it. Doing the side flutes of an end mill would be beyond it. Lathe tools would need to be rough sharpened off hand in the usual way also you have hollow grind with a narrow section at the proper angle.

Although I'm quite impressed by what Harold Hall has done to extend the basic "Hart Style" parallelogram arm pivoting tool rest I can't help feeling that objectively its not the best approach.

I am surprised that no one has come up with a low end electronically controlled or CNC one yet. Handwaving estimates suggest that sub Worden prices for something pretty versatile should be possible. After all the control only needs to generate simple vector paths.

Clive.

I would also like to be able to sharpen my own tools and have looked at lots of designs and the price of commercial units and decided to build my own. It is still in the development stage at the moment using features which I have seen in other designs.

Paul.

Plans for this one are available at

http://www.ebay.com.au/itm/Tool-cutter-grinder-PLANS-Acto-/302115704341?hash=item46577fce15:m:m_X1hNGyFu1wh_cQQMHrKbw

Edited By Paul Lousick on 26/10/2016 23:18:19

Another consideration is that, although cutters are relatively cheap, they are not necessarily there when you need them. That is, if you are into a job and find that you need a sharp, new cutter to replace the blunt one you have, you have to stop and go get one (assuming you have a local supplier and he is open today). With (some kind of) cutter grinder, sharp cutters are always available.

Whether that justifies the cost, only you can say.

Replies to various questions and posts.

Firstly the Vertex type T&C grinder than everyone and his dog calls a Universal Cutter Grinder, isn't.

It's a clone of a Deckel / Alexander single lip engraving cutter grinders and has quite a few major flaws when trying to grind slot drills and end mills.

You have two positions to grind a tool, on the flat end face of the 4" dished wheel or the periphery.

End face first. To grind the RH side flute so the other flute is off the wheel in fresh air means you need to angle the cutter down. Something like 5 degrees for the cutting angle and 20 odd degrees for clearance but the movement is designed for a tip up attitude and not tip down. In fact most wont go below 12 or 15 degrees and by the time you have the cutter sticking out the collet you have run out of room to actually fit it in.

Peripheral face next. Because the wheel head is at a fixed height and the same for the guide bar controlled collet system the angle that can be applied to the cutter is determined by how far out the cutter is. On something like a long 1/2" cutter sticking out 1 1/2" the cutter will be touching the top of the periphery and probable be grinding at a 45 degree angle.

Unlike a grinder with a column like a Quorn, Clarkson or Boxford these cannot place the wheel and cutter in the correct plane because they were not designed for this job - simples.

Clive asks about a CNC version but Alan ? Pace did one in MEW that just sharpened the flutes and glossed over doing the ends.

He states " Handwaving estimates suggest that sub Worden prices for something pretty versatile should be possible"

However I have just looked a Worden up and they are £400 for the kit of which probably 1/4 is the wheel and motor which leaves £300 for ball screws, motors, drivers, a controller and all the respective mechanical bumf like work and wheel for the 4th axis part.

Sorry not going to happen as it costs as much to build a small CNC as a large one.

Anyone wanting a nice T&C grinder with loads of bits, done a genuine 5 hours from brand new PM me and get it out my way.

Edited By John Stevenson on 26/10/2016 23:22:18

Greetings,

many years ago, I built a Stent, from partially machined castings, obtained from Blackgates. I should say that I mainly build locos.

I didn't use it that much because of the seeming endless supply of second hand endmills that came from factory closures, but I did start to use it,because I started to value the the quality of cut obtained from a super sharp end mill, and my "endless supplies" dried up when I moved.

I have now completed a 4 facit drill grinding jig, designed for the Stent, and I have to say it is now in almost daily use.

So, is it worthwhile to own one, the answer must be yes, if you are going to be a model engineer, rather than just using the machine tools to make odd items.

BB

Morning all,

Although fairly green at the art (and sometimes grit..) my need for tool shapes have been fairly basic and I am competent in sharpening what I need on a very basic set up. Now things are getting more interesting with more complex tasks, but...

Sharpening seems to generate large amounts of dust and dirt that are probably pretty abrasive, and very messy. In a multi use workshop, dirt matters: swarf is bad enough, but the muck from the grinder is on a different scale. I am also concerned about fire risk, with hot sparks near various paints, solvents, gas, meths and occasional sawdust.

I really don't want to set the grinder up permenantly in my small and (mostly) clean workshop, so I use it in a temporary rig outside, weather permitting.

Predictably, I have now fallen under the lure of indexable tips... but some on here seem to frown on this.

So what am I doing wrong?

Matthew

Edited By Matthew Reed on 27/10/2016 08:41:59

Availability of the sharp cutter is why we lust after the cutter grinders. I do not have one but have access to both a Deckle single lip cutter grinder and a Pratt and Whitney cutter grinder. The Pratt & Whitney was supplied with a "Keller" copy mill and can do ends/flutes/angles plus internal/external radius. I would pay good money to have one of my own but have never seen one for sale.

Years ago used to use a small floor standing Pratt and Whitney T&C grinder. A very versatile little machine which we used for small end mills/slot drills and ball end Keller die sinking cutters etc. It was the most used of all the machines in our T&C department. Like Chris, I have never seen one for sale either.

I have an idea that the examples found here possibly came over from the USA during WW2? If you are lucky enough to track one down cheap look for the angled tool head and its set of rubberized collets otherwise its functionality will be drastically reduced.

Rik

Posted by John Stevenson 26/10/2016 23:20:51

"Clive asks about a CNC version but Alan ? Pace did one in MEW that
just sharpened the flutes and glossed over doing the ends."

Yes he is right ,the reasons why the ends were not included is because
the machine uses the Quorn workhead and as such the ends can be
sharpened on the Quorn.The ends could be done on the cnc machine
but would it be really worth the effort to write an additional part to a file to
do it.

I don't think that some have grasped the difference of the type of
cnc machines that are used for the production of new cutters and
requirements of a similar machine in a model engineers shed.

A machine making new cutters picking up blanks ,loading and then
grinding them all over and them returning them to the tray is somewhat
different to rummaging around in an ice cream box to find an old
cutter and returning it to a new cutting condition ,i do this all of the time.

The article for this machine was published in 2008 ,i had hoped that
it may have given others some insipiration to work on something
similar ,instead you see the same old methods used , here is an
example from one such.

"The clearance is set by tilting the table down on the right but just
setting this to the required angle is no guarantee that the clearance
angle on the cutter will be correct. For this the cutter must also be
set as shown in Sk. 8. If, having sharpened the spiral cutting
edges, the cutter fails to cut as you would like, almost certainly
the clearance angle is insufficient. For smaller cutters you may
need to provide secondary clearance."

Oh dear not very good is it.
An excerpt taken from the text of a well known cutter grinding attachment.

It is worth pointing out that the cnc machine has a resolution of 1 /20 th
of a degree and as such the clearance angles can be set as such
and yes it is verifiable.
I feel that this not bad for a machine made mostly from scrap material,
the main base is from two pieces of channel steel welded together.
Photo's in album "Quorn an cnc grinder".

It works similar to the demonstration in this video.

www.youtube.com/watch?v=qxU0K-TmEvI

Obviously this machine has a much better operating system to be able to do this ,
something that would be unlikely to be seen in the home workshop and i expect
beyond home workshop budgets.

Getting back to th OP's original question ,I suppose it really depends on whether
you are just out of your pram or a coffin dodger.
I built my Quorn around 1985 or so i think it was about £350 a lot of money then,
Divide that by the thirty odd years that i have used it = £11 .66 and all of the cutters
and other jobs that have been done over that time ,seems like a good deal to me.

John

Hi Bandersnatch, you make a good point regarding availability of a sharp cutter when needed. But I would say most people carry more than one cutter of a particular or popular size and how often would the incidence of not having a cutter available occur?

Seeing John Stevenson's message earlier in the thread reminded me of the great service John performed at the recent Doncaster show. I took advantage of John's kindness and for a charitable donation got a handful of cutters resharpened. Maybe this could be a possible solution. If say a vendor like RDG offered a similar service at shows, I for one would be prepared to pay a reasonable cost to get some cutters resharpened. Obviously one can use your local engineering tool shop, but most are not geared up for small one off infrequent customers and would probably either not bother or charge a disproportionate amount. John, are you intending to offer your kind services again at next years Doncaster show? Or has the popularity of your last offer put you off. I was at Doncaster on the Thursday and Sunday and on both occasions I noticed how busy you were and also the queue at your stand.

Alan.

I don't know about spending hundreds of pounds. I got my Union T and C grinder for free. The mechanical workshop was getting rid of a vertical mill and wanted shot of the grinder at the same time. The machinery man wanted the mill for resale but was only taking the grinder out of courtesy and was not willing to pay anything. Said he could not give them away. So I had it instead free gratis and for nothing so it can be done.

regards Martin

.

Thanks for the very logical 'justification', John

I must re-visit that article.

MichaelG.