Hi Fred,

Quorn or Stent? Let me start the ball rolling …..

I too had the same dilemma – I wanted a small T & C grinder, but was it to be the Quorn or the Stent? In the event, I chose the Quorn and completed construction over a period of several years. The Stent as designed is a fairly crude machine whilst the Quorn appears to be far more sophisticated. 

Was this the right decision? Although the Quorn will carry out many operations, particularly with special attachments, I have become increasingly frustrated with it. The main reason being that, apart from movement along the bed bars, other movements involve the generation of arcs rather than straight lines and therefore there are no graduated linear scales.  This makes it very tedious to use (for me anyway). The Stent on the other hand has normal linear movements and graduated scales.

I had decided to stick with the Quorn until I read an article by Charles Woodward in MEW 137 (April 2008), in which Charles appraised both machines and described how he had modified the original Stent design into what might be termed a ‘Super Stent’. This is well worth reading and may help you to make the final decision.

Charles has now written a further series of very helpful articles, currently being published in MEW. There has also been a series of articles on using the Clarkson in recent issues of MEW and as the Stent is based on the Clarkson, these too have been very helpful.  

My problems were resolved, and I decided to build the Super Stent, but with a few more modifications of my own – primarily to utilise the Quorn principle of interchangeable wheels and maybe some of the tooling (as I already have these). This now involves some more redesign, particularly the spindle which needs further ‘beefing-up’ due to the hole required for the drawbar. Detail design work is now well under way for the main assemblies, and I hope to start cutting metal shortly.

Overall, my own opinion is that properly ‘tooled-up’, the Super Stent is the better option, although I’m sure that the two machines will compliment each other, with some jobs being better done on the Stent and some on the Quorn. Hope that this helps – what do other people think?

Prices – a shock here I’m afraid. I bought my Stent casting set from Blackgates in July 2008 just after a price increase due to foundry costs – cost of castings and drawings was around £320. I believe that Quorn casting prices are very similar.

Regards.

Edited By NJH on 07/09/2010 23:36:39

Am I right in thinking that GHT had some early input to the design of the Stent?

I recall his bemoaning the fact that his Quorn castings were taking root on the shelf.

The Quorn design has been built by way of fabrication and, presumably, so could the Stent.

Hi Guys,

I've been building a modified "Brooks" TCG ! I will have been at it for two years come next March.

I've used ball races instead of the precision ground bars and made my own spindle design. If I was doing it again I would go the whole hog and use dovetail guides and gib strips. I've done a WIP on another forum along with drawings and photographs.

I'm now into things like control knobs, tool holders and assorted wheel hubs.

What do you want to grind? I have a Quorn that I inherited and almost never use because it's so fiddly to set up. I have also built an Acute grinder from EE which will shape lathe tools and sharpen the ends of end mills and slot drills. The only thing in principle a Quorn does extra is sharpen flutes but it doesn't do that very well unless you make additional accessories. Personally for the home workshop I think the Acute is brilliant, a kit is cheaper than a Quorn or Stent and made in Australia!

Initially, I wanted to make a Quorn, but lacked the confidence for some of the operations, (The coarse thread on the column for instance ) but took the chance of buying a secondhand Worden kit, which had been started to extent of drilling a few holes oversize. This was an easily overcome problem. The holes were not symmetrically placed, so turn the bars end for end, and redrill to the correct tapping size!.

Consequently, the Stent was never ordered or made, although that was my second choice had the Worden been an offer not to be refused.

Howard

I have the full set (as far as I know) of articles for the Stent courtesy of IanT. If anyone want's .pdf copies send your email to me via messenger here and I'll get them over.

Hi Howard, I think using an existing collet system like ER20 makes perfect sense for any tool grinder setup. In addition to your point about the range of diameters which can be held, the collets will hold the blanks more central to the holder axis and more securely than holders with setscrews or side clamps.

For square tools or rectangular tools, are ER style collets available? If not, conventional holders would be needed for those tools. (preferably V block style, clamp pointing toward the vertex of the V)

I would urge caution to anyone following Charles Woodward designs. I have looked at his work over the years and it seems to me that he frequently finds the very longest and most involved way to do things and forgets about location and friction. Just my opinion.

Lately I have been looking at the design and construction of various Chinese made universal tool grinders. The one in the link below uses 5C collets. These grinders have copies of many of the better features of US, British and German made professional tool grinders of 60-70 years ago, but at a very reasonable price if you wanted to buy one. I noticed there is nothing in the design which could not be fabbed from bar stock/plate in a home workshop. If based on the mentioned industrial machines, there will be nothing you don't need, and nothing missing that you do need, in terms of work position envelope / range of angles etc. Just food for thought.

https://www.shars.com/universal-end-mill-cutter-drill-bit-grinder-sharpener

Hi Howard, No, juggling eight or even four little shim bars in a collet during setup doesn't appeal to me either. The L shaped pieces might work OK but not sure how an ER style collet would apply clamping force evenly to the setup. Maybe a holder with the outside geometry of an ER collet, and a V groove for the item to be ground, would work. Clamping might be possible with a loose piece the collet nut secures/ wedges on, or by a bridge clamp built into the V grooved insert. Might be getting small in size for adequate strength threads and screws, though. Interesting to think about.

Rotary broaching is well worth playing with a bit, and good fun. If you do one, be sure to look up Mike Cox's simplified method from MEW a few years ago. Good results with minimal work to make the necessary bits. I did a nice pentagonal one with the points coincident with a 5/8" diameter circle a few years back for a neighbour in the waterworks service business. He was getting breakages in expensive commercial socket wrenches with the pentagonal socket, scrapping one about every two weeks. I made him a couple in D-2 tool steel, surface hardened and their crew is still using them daily! 

Another way might be to make the tool grinder accept an interchangeable large rectangular block with the socket geometry for the ER collets OR a rectangular block with groove and clamp for rectangular work OR a block with central bore for holding cylindrical tool holders. If all such blocks were located by 2 dowels on a nice finished planar surface (vertical, to shed grinding dust easier) and clamped with a bridge clamp this would make a very versatile unit. (probably been done centuries ago but I am just mentally arriving at how the old timer tool designers did them!)

Rotary broaching is well worth playing with a bit, and good fun. If you do one, be sure to look up Mike Cox's simplified method from MEW a few years ago. Good results with minimal work to make the necessary bits. I did a nice pentagonal one with the points coincident with a 5/8" diameter circle a few years back for a neighbour in the waterworks service business. He was getting breakages in expensive mild steel  commercial socket wrenches with the pentagonal socket, scrapping one about every two weeks. I made him a couple in D-2 tool steel, surface hardened and their crew is still using them daily! 

Cheers Jeff

Edited By Jeff Dayman on 21/12/2020 17:40:24

That sounds a good idea, Duncan,

It would avoid for having to evolve a third hand!

Take up Rotary Broaching and then slit!

Another item to go on the Round Tuit!

Thanks

Howard

Edited By Howard Lewis on 22/12/2020 13:53:39

I had a look at Mike Cox's web site and had a go at making one – but I made the rotary part out of a redundant revolving centre mounted in a mild steel block machined to fit on my QCTP. It incorporated the necessary angles in its flank and rear face. Photos and brief construction description in my album entitled Rotary broaching tool

Incidentally, I was the author of the article referred to by Howard, suggesting using various sizes of rods to hold square stock in round collets. In my defence and of those of us with only two hands, it was said in the article that it wasn't supposed to be a long-term solution to the problem, but a stop-gap, one off, temporary arrangement.

John