Machining Setup's with Few Comments

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Wolfgang
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Re: Machining Setup's with Few Comments

Post by Wolfgang » Tue Dec 05, 2017 11:45 am

Shimstock is your friend for making up small differences in mating diameters.

I, too, built a Quorn T&C grinder and took the designer's advice and split the 1" dia arbour mounting head so as to clamp any work holding mandrel. Big mistake as the hole opened up a few thou.

Should have left well enough alone as the bore was a very good fit on the 1" dia drill rod I had for the work mandrel. A cotter clamp, similar as used on many lathe tailstocks would have been better.

I also made a #2 Morse taper socket arbour for my Quorn grinder, proceeding as follows:

1) Made sure that I had on hand a Morse taper drill chuck arbour with a center hole in each end. Verified that the O.D. of said arbour is dead nuts concentric to the center holes.

2) Chuck appropriate piece of round stock in lathe (I prefer 1144 steel for this sort of job) and drill, bore, and finish REAM the #2 MT socket bore. Be sure that the through hole is big enough to clear your smallest dead center for your lathe.

3) Mount the embryo MT socket on the chuck arbour and turn the O.D. between centres.

Voila! w

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Wed Dec 06, 2017 2:11 pm

Drilling blue tempered spring steel using the sandwich approach. Nothing that has not been done before but just to show how good it can turn out.

Just use two pieces of scrap aluminum clamped as shown and centered in the vise of the mill.

Start with a standard HSS center drill to start/locate the hole, followed by an undersize carbide stub drill, followed by a standard HSS jobbers drill.

That hole is clean with no burrs or any distortion at all.
Attachments
364 The Blue Tempered Spring Steel Strip After Drilling.jpg
365 A Clean Drilled Hole - No Burrs or Distortion.jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Tue Apr 24, 2018 1:40 pm

Some photos of a recent slitting saw operation. The new, hollow ground slitting saw was 0.020" wide and the saw cut was approx. 0.325" deep in mild steel. The two identical stepped plugs shown in the first photo are made from 01 alloy steel heat treated and hardened. They are used to align the angle plate square to the tee slots of the mill's table. I find these plugs very useful and use them all of the time (I made four of them).

Use plenty of cutting oil and run the slitting saw slowly. I only took about a 0.005" deep cut per pass so as to ensure the saw blade would not wander.
Attachments
367 A Slitting Saw Setup.jpg
368 Slitting Saw Setup.jpg
369 Slitting Saw Setup.jpg
370 Slitting Saw Setup.jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Fri Apr 27, 2018 8:46 pm

The finished part - the indicator body clamp piece. It was a lot more work than it looks. I would not want to be making parts like this for a living.

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Fri Apr 27, 2018 10:19 pm

The photos.
Attachments
372 Fowler Verdict Indicator Finished Body Clamp Piece.jpg
373 Fowler Verdict Indicator Finished Body Clamp Piece.jpg
375. Fowler Verdict Indicator with Dovetail Clamp as Shown in the Neill Tool's Catalogue.jpg

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Fri Apr 27, 2018 10:52 pm

You don't want to make this. Guaranteed to push you over the edge in frustration.

If you want to know, see the May/June 1988 issue of the Home Shop Machinist, starting on page 52, the construction article entitled "The Surface Grinder" Part 4 by R. A. Washburn.
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376.jpg
377.jpg
378.jpg

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GlennW
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Re: Machining Setup's with Few Comments

Post by GlennW » Sat Apr 28, 2018 11:13 am

What might it be?
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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Sat Apr 28, 2018 1:42 pm

Hi Glenn,

Don't get me going on this! :D

It is the custom made adjustable guide which goes with the Washburn end mill sharpening fixture for sharpening the primary and the secondary relief angles on the end of an end mill flute to resharpen a worn cutter. The alignment guide is used to set the face of an end mill tooth truly perpendicular to the side of the grinding wheel.

I have a commercially (USA) bought unit which I am adapting the Washburn guide to fit. All of the available commercial units have severe limitations (which nobody talks about) which limits their usefulness on a surface grinder. Robert Washburn was the only writer I know of who tried to solve their inherent problems by constructing the adjustable guide. We are just talking about sharpening the end faces of an end mill here - not the spiral peripheral cutting edges. I use mostly HSS end mills as they can be sharpened multiple times (with limitations - I have written about this elsewhere) using relatively cheap standard aluminum oxide wheels.

I cannot operate without having absolutely sharp end mills. Even the Washburn adjustable guide does not solve all of the problems inherent in end mill sharpening using only a surface grinder. The primary and secondary relief tooth angles are the easiest to do but there is also what I call the third facet (usually set at 88 degrees to an end mill tooth so that the 90 degree corner of a straight grinding wheel (and it truly has to be dressed to 90 degrees) will not touch an adjacent tooth cutting edge (for two flute end mills only - it becomes more restrictive with 4 tooth end mills and even more restricted with an end mill having more than 4 teeth). The third facet is required to remove material ahead of a cutting tooth edge so that it can cut. Everyone forgets about this but your end mill won't cut for long without dealing with the third facet also. Look at a new two flute end mill and you will see what I am trying to describe.

Also, there is the problem of how does one find the exact center of a center cutting end mill especially one which has been previously re-sharpened and now is undersize (on diameter)? I am fortunate that I can trust the infeed micrometer dial on my surface grinder or you can go all digital with an electronic edge finder at great cost.

I am slowly solving all of these problems but am not there yet.

If anyone is interested, I have written a tome on all of this on the Homemade Tools website. I use the same author name there as I do here i.e."carrdo".

I do have a Quorn T&C grinder which I am trying to figure out how to use to do the above as well. Just FYI, I nearly created a riot with the Quorn T&C grinder group found on Yahoo (where I am a member also) when I said that the Quorn wasn't up to the job. I said just prove me wrong but nobody has so far.

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GlennW
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Re: Machining Setup's with Few Comments

Post by GlennW » Sat Apr 28, 2018 6:08 pm

Are you referring to the "Axial Rake Angle"?
endmill3.gif
endmill3.gif (1.97 KiB) Viewed 1011 times
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Operating machines is perfectly safe......until you forget how dangerous it really is!

pete
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Re: Machining Setup's with Few Comments

Post by pete » Sat Apr 28, 2018 6:25 pm

I've got Prof. Caddocks book on building the quorn Carrdo. You may or may not know there's been a fair amount written in the U.K. published Model Engineers Workshop magazine about using and extending it's capabilities. A digital subscription to the magazine will get you access to every one of those back issues on the Magazines form website in case your interested. I suspect but can't prove that the Deckel single lip cutter grinder had a fair amount of influence in the Quorns tool holder design and method of setting the various angles. From what I've only read most of the highly experienced Quorn users will say there isn't much it can't sharpen, but it's time consuming to set it up properly for different tasks.

Possibly it's old information and you already know of it. thebloughs.net has some Quorn information, and Martin Model & Pattern offer castings to use 5C collets as the main tool holding system in case that helps.

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Sat Apr 28, 2018 9:07 pm

Hi Glenn,

On your diagram, the end gash is what I normally refer to as the third facet. Terms are very confusing, as used by different people, and need to be explained fully. With a two flute end mill, a straight 90 degree corner grinding wheel can be used to gash to the center of the end mill but with a 4 flute end mill there is not enough room between the end mill teeth to get the 90 degree corner of a straight wheel to gash (as in your diagram) to the center of the end mill without the grinding wheel touching the next tooth which is a disaster. I have destroyed many cutters this way so I know.

This is where T&C grinders use a flairing cup (highly tapered) wheel for two and four flute cutters for the end gash operation. With cutters having more than 4 flutes, there is now so little room between the adjacent teeth of the cutter, very narrow wheels have to be employed to do the gashing operation. It all gets much worse when the diameter of the end mill is less than 1/2". You can't get away with what is possible on a large diameter cutter, on a small diameter end mill and I use a lot of them.

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). In the Homemade Tools web site (www.homemadetools.net), in my series of articles there, you can see a photo of an end mill that has been "end gashed" by me (as I call it) which quite radically modifies the end of the end mill by cutting a narrow transverse slot right through the center of the end mill. Why do I do this sometimes? I explain my reasons for doing this in the articles.

Regarding the axial rake angle, it is modified (for worse) and then lost by repeated sharpening of the spiral cutting edges of the end mill (which also reduces the OD of the end mill making it undersize). I use many re-sharpened undersize end mills all of the time and love them. An end mill with no axial rake angle left will cut very poorly, if at all. In my articles, I give a series of sketches of how axial rake is lost through repeated sharpening of the spiral cutting edges of an end mill. But it is worth doing if one has the equipment (a quality air bearing spindle and a surface grinder) as I can get up to 4 regrinds if I resharpen an end mill when the spiral cutting edges are just somewhat dull and don't push the end mill beyond this point as most people do.

I am also working on a method where the spiral cutting edges of a HSS end mill are never sharpened - only the end teeth. It has its limitations but this way I can sharpen an end mill like a lathe tool - literally dozens of times and use up the entire cutting length of the end mill in the process.

I do the same thing with 30 cent HSS drills to use them up entirely - I am very cheap.

In industry, time is money so it is not worth the effort to keep the equipment and people to sharpen HSS cutters anymore as they don't stand up to the speeds, feeds and depth of cut vs modern coated specialty carbides and other exotic cutting materials which are now used. But in a home shop things are different.

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Carrdo
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Re: Machining Setup's with Few Comments

Post by Carrdo » Sat Apr 28, 2018 9:44 pm

Pete,

I have Prof. Chaddock's Quorn book and an entire thick file of what additional things the Quorn is supposed to be capable of doing. Most of what is shown is "staged". Yes, the Quorn will grind the primary and secondary clearance angles on a two flute end mill - I have got that far on my Quorn also but this is the easy part. It is also very fiddly and time consuming to do (the lock/unlock ball handles and the resulting work head movements have to be very, very precise and positive and easy and they not always are) but with practice I am getting faster.

What the Quorn won't do well at all (unless somebody out there can prove me wrong) is the gashing or third facet operation. One can't use an end mill for long without getting into this operation also.

I want a blow by blow description with all of the associated photos as to what the gashing setup looks like and how it is done on the Quorn. I have issued a challenge (in 2017) to the Quorn Owners Group over this issue but so far no one has come back at me. Just a lot of outrage.

Yes, the Quorn design was likely an outcome of the Deckel SO single lip grinder. The Deckel SO machine can be modified to grind the ends of end mills and drills and some enterprising Deckel owners have made the necessary modifications to do this. I have corresponded with them and it is the same thing, they are only grinding the end mill cutting edges primary and secondary clearance angles.

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