Machining Setup's with Few Comments

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pete
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Re: Machining Setup's with Few Comments

Post by pete » Sat Apr 28, 2018 10:09 pm

After a thought then with all the time and effort into building a Quorn from a set of casting it's probably not surprising some photos of what it could or maybe should do are staged. I'd be trying to justify all that work myself. :-) Interesting to get some opinions about it being not quite the machine were led to believe. It now sounds like finding a fair priced used Cinncinati tool and cutter grinder or other compareable machine "if" you can get the other accessorys might be the better option. That if part is the tough one since most know what they have and price it accordingly.

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GlennW
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Re: Machining Setup's with Few Comments

Post by GlennW » Sun Apr 29, 2018 5:59 am

Carrdo wrote:
Sat Apr 28, 2018 9:07 pm
I also use the term "end gashing" (but with me and with what I do; that is a 4th and quite different optional operation to what is shown on your diagram).
The "Gash" is what creates and dictates the "Axial Rake Angle".

Now I understand what you are doing, as I couldn't understand what "third facet" would need to be addressed for normal sharpening of an end mill, but you are not doing what i would consider "normal sharpening".

I might touch up the end of an an end mill once during it's life, as I usually use a cutting depth of around 1/2 diameter so the sides get dull. It's not worth the effort to cut that much off of an end mill and start over in order to get to sharp side edges to keep the original diameter. If you are using very light depth and just wearing the corners of the end mills I could see possibly grinding it back and re-gashing it.

Heat is the main enemy of cutting edges, in that a cutting edge does not know what depth of cut is. Taking .050" depth of cut on a cutting edge and making ten passes to remove .5" is ten times more wear on that cutter than one pass at .5" depth of cut. Obviously, this is a general statement and does not apply to all materials and situations, but the object of the game for cutter life vs material removal rate with HSS is to take as deep a cut as possible and keep it cool. (I know, nobody likes flood coolant!)
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Sun Apr 29, 2018 9:50 am

Hi Glenn,

Since I am retired and do machining only as a hobby, my time is worth $0.00. And since I have already paid for all of the potential sharpening equipment here (during my working years), for me, it is worth it to try and resharpen all of my HSS end mills since they are costing me $0.00 also and there are enough of them to keep me going long past when I will be with us.

I take only light surfacing cuts (a 0.020" depth of cut is a heavy cut for me) as the Millrite is considered a light machine and it is not new and has wear but it is still accurate if I am careful. So one has to tailor one's methods to the equipment one has (or hasn't) and as well I am trading time for $$.

If I can produce very sharp end teeth on my HSS end mills, I can achieve a very fine surface finish and everything will end up truly square, parallel, straight and flat, have uniform thickness, etc. and that is good enough for me. I don't have to and I don't remove cubic inches of metal for the model work which I do.

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Sun Apr 29, 2018 11:00 am

For completeness, the Quorn setup to grind the secondary clearance on a two flute end mill.

As you can see, it is not the easiest thing to achieve.

The heavy rectangular mild steel plate shown in the photos is a quick and dirty method for aligning the Quorn spindle head/cup grinding wheel square to the bed bars of the machine. The purists in the Quorn Owner's group didn't like that either.
Attachments
92 The Quorn Setup to Grind the Secondary Clearance on a Two Flute End Mill.jpg
89 A Quick Way of Aligning the Quorn Grinding Wheel Square to the Bed Bars.jpg

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GlennW
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Re: Machining Setup's with Few Comments

Post by GlennW » Tue May 01, 2018 12:30 pm

That's a really nice indicator clamp you made, as well as your Quarn!

That looks like an interesting grinder.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Wed May 02, 2018 8:27 am

Hi Glenn,

The Quorn.

It took me 15 years to make it as it needs a million and one accessories to be useful after constructing the basic machine. Still do not have all of them.

The problem is with all of the secondary tooling and special fixtures, cutters etc. which are needed to produce it to the required standards. This is a machine where everything has to be dead square, parallel, straight, on size, the castings are very awkward and difficult to hold and machine, the problems just go on and on.

Also, it is not that heavy a machine and far less rugged than a commercial T&C grinder.
Attachments
84 January, 2018 - Overall View of the Quorn.jpg
87 Additional Quorn Items on the Floor.jpg
51 My MK 1 Quorn T&C Grinder June 2011.jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Mon May 21, 2018 8:05 pm

One more completed step in my end mill sharpening quest.

The finished Washburn retractable mounting guide adapted to my commercial end mill sharpening fixture to be used in conjunction with a surface grinder.

The retractable guide aligns a two or a four or a six flute end mill tooth cutting tooth edge (or any even number of teeth) exactly at right angles to the grinding wheel. With the commercial fixture alone, one has to do this by eye which is iffy at best.

I made the retractable guide as a complete separate unit as my commercial end mill grinding fixture is different to the one described in the Washburn articles. To incorporate it as part of the end mill grinding fixture (as shown in the Washburn articles) would have required further modifications and I have done enough of that already. It is also more flexible this way as I can easily shift the retractable mounting guide sideways in relation to the grinding fixture which makes the aligning of different diameter end mills much easier.

One can easily align an end mill down to about 1/8" diameter. Below that size, the length of the end mill cutting edge becomes so short that some sort of magnification would be needed to clearly see what is happening with the alignment.

I can describe how the alignment is carried out if there is any interest as there is not a lot of detail given in the original HSM articles.
Attachments
93 The Finished Washburn Rectractable Mounting Guide.jpg
94 The Finished Washburn Rectractable Mounting Guide.jpg
95 The Finished Washburn Rectractable Mounting Guide and End Mill Sharpening Fixture.jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Mon May 21, 2018 8:20 pm

One more photo showing the critical aligning feature on the retractable guide.
Attachments
96 The Critical Aligning Feature.jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Mon May 28, 2018 9:13 pm

Grinding a compound angle on a 1/2" square HSS tool bit on the surface grinder. The tool bit is for a fly cutter and the tool bit angles are not all that critical. Just make the tool bit angles large enough so that the tool shears the metal and doesn't rub it. For home shop use that is all you really need to know. If a freshly ground tool bit isn't cutting the work (it is rubbing), increase the clearance angle(s). Yes, it may weaken the cutting edge a bit but at the speeds, feeds and DOC (depth of cut) I use, it doesn't matter a hoot. With very small diameter work, in a lathe for example, clearance angles can become extreme (>30 degrees).

It is said that fly cutter tool bits, properly ground and sharp, give near surface grinder finishes but I have not been that successful to date.

Now, how one can do this by hand on a bench grinder is beyond my comprehension but some people can.
Attachments
97 Grinding a Compound Clearance Angle on a Half Inch Square Toolbit.jpg

pete
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Re: Machining Setup's with Few Comments

Post by pete » Tue May 29, 2018 11:10 am

Some really well thought out grinding attachments Carrdo. If I had a surface grinder I'd be copying some of those. :-) Unlike yourself and going by some of the Youtube video's I've seen many don't seem to understand flycutters are a finishing tool. Quite a few posts on the PM forums mention that and how they can be hard on the splines and bearings if enough roughing is done with them. Fwiw I limit mine to .010" or less doc and found a large tip radius gave the best results. Some YT videos mention taking .050"-.100"per pass and you can hear the splines hammering each time the tip starts into the material. I found a fly cutter that uses round replaceable carbide tips that seems to cut very smoothly and produces pretty good surface finishes on most materials. It's dirt cheap to use since the carbide tip can be rotated a bit if the edge gets dull or chipped.

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Tue May 29, 2018 3:00 pm

FWIW I could not live now without the surface grinder. I have become spoiled. I use only a 0.005" DOC with a large tip radius and get a very good finish but yes, I have seen surface grinder like finishes using a fly cutter only.

I have a small problem with the Millrite mill here as the aluminum motor pulley sheave has a slight wobble which limits my top speed hence I am stuck with HSS at the moment. Another job waiting for me to re-bore and re-bush it (it is over 6" thick) and then turn everything between centres to have all the pulley surfaces dead concentric. Another friend had his Millrite pulley sheaves sent out to be dynamically balanced at a commercial establishment. Not cheap, but he said it made all of the difference in the world. But then, he does commercial machining.

Cary Stewart
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Re: Machining Setup's with Few Comments

Post by Cary Stewart » Tue May 29, 2018 5:36 pm

IMHO The Quarn T&C cutter machine is a wonderful piece of design and if done well is very versatile. However, I think that using it is like using a pre WWII Leica camera. Build quality super. But the need to be an engineer to operate a IIIa, etc. is kind of a pain. I inherited two of them from my Uncle in Chicago in 1979. I put a few rolls of film through the best of the two and the photos were beautiful in black and white but not quite up to the task in Kodachrome. For the average photog. Getting ready to shoot a pic takes a while. Same with the Quarn. It will do a super job once set up but that takes a while.
Cary

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