Sharpening drills with a tool grinder

Today, I fixed an old Rockwell tool grinder, looking extremely similar to this:
http://goo.gl/M7uws (Baldor.Com)
and this:
http://www.harborfreight.com/1-2-half-hp-6-inch-tool-grinder-46727.html
It had some cast iron pieces broken off, it was not a big deal to fix.
Anyway, now that I have it working -- I will put it on a VFD -- I wonder what can I do with it.
I am aware that use #1 is to sharpen carbide and HSS lathe cutters. That's quite obvious and seems easy.
What I wonder about is how to sharpen drills with it, if it is at all possible. I have two bad carbide drills, for instance, and two identical but unworn ones. They look easy to regrind, as the grinds are completely flat. If I just do it by hand and the result "looks" centered, will that be good enough?
For more regular drills with curvy shape of cutters, are there any attachments or things that I can use to grind them on this grinder?
i
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I've got the same unit. Its great for lathe bits, lathe boring tools, and my devlieg boring bars.
I've never used it for drills. No reason you couldn't free hand them just like on the bench grinder.
Karl
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Does anyone know where you can buy Al oxide metal backed wheels for these machines for less than $100?
Chuck P.
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Ah, iirc, JTS Tool. http://www.jtsmach.com has them. I bought one a couple years ago from them.
Wes
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Do you have a diamond wheel for it? If you try to sharpen carbide with silicon carbide wheels (aluminum oxide won't work), it will work, more or less. But you'll have a hard time trying to get a sharp edge.
As for cutter jigs, consider making a Quorn. It's a great project.
--
Ed Huntress



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I have one of these Toolmaker surface grinders, whose head is a mirror image of the Quorn:
http://www.ozarkwoodworker.com/images/AdPhotos/dsurfacead.jpg
The mag chuck can be replaced with a swivel table with centers for sharpening tools with center holes. Harig made a drill sharpening fixture that resembles the Quorn's work holder, but they sell for too much at auctions. They use cams like a Drill Doctor to shift the bit axially as it rotates.
http://modelenginenews.org/meng/quorn/drilljig.html
I also have most of a pedestal grinder originally built to sharpen large drills. It appears to have been a large and solid implementation of the General drill grinding fixture design, which grinds a conical back relief.
http://mkctools.com/mvc-121e.jpg
I made a fixture to grind a flat cutting edge on large S&D bits on the surface grinder, but haven't dulled one yet. https://picasaweb.google.com/KB1DAL/Tools#5288898039281271986 The black piece is a commercial end mill grinding fixture, I made the hollow collet closer nut etc. The drill shank hangs off the side of the mag chuck. This fixture grinds 120 degrees, not 118.
Perhaps you could jig a square collet block on your grinder's table for the same result.
jsw
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The TDR-SRD drill resharpening machines use a somewhat unique square-shaped chuck/holder for drills. http://www.drill-grinder.com/storefront/Scripts/prodView.asp?idproduct 
http://www.drill-grinder.com/rep_grinding_wheels.html#Replacement_Drill_Chucks
The square shape of the holder insures that the two-part operation can be completed with an accurate separation of 180 degrees. The operator is required to make the proper rotational position setting (scored reference lines provided on the block), otherwise the leading edges/lips of the lands (or flanks) are improperly positioned.
The more unique aspect of the TDR-SRD machines is that they use the ID of a small high-speed cup wheel. The small motor allows the machine to be easily portable (~50 lbs.). The angle and elevation are adjustable for any drill point geometry, and a few other cutting tools such as countersinks.
A square-shaped block is also used with the Veil resharpening attachment, although the block pivots/swings on a bearing hole that fits an adjustable post (not utilizing the outside of the square holder for alignment/positioning). The S-12 drill sharpening attachment is intended for their S-5 belt sander-grinder, but can be modified for use with almost any common grinder. There are 2 holes in the block/holder halves, so again, it's a two-part operation, one for each land.
http://www.vieltools.com/detail.php?p=NTUw
--
WB
.........


"Jim Wilkins" < snipped-for-privacy@gmail.com> wrote in message
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My square 5C block measures 1.750" across, so a 7/8" parallel could serve for the edge setting gauge.
John Stevenson who used to post here makes an ER collet holder with a 5C shank: http://www.arceurotrade.co.uk/Catalogue/Collets/5C-Fixtures/Stevensons-5C-Indexing-Head-with-ER32-Nut-and-Adaptor
I had some problems with chatter when using a cheap spin index on the grinder. It only worked well with the spindle fully retracted: https://picasaweb.google.com/KB1DAL/Temporary#5289374956505595074
jsw
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wrote in message

Very cool.

That would be good reading for Iggy.

I have the General version. It's Ok, for non-critical work.

I'm not following that completely but it may be the same thing we had in the job shop of which I was part owner back in the '70s. I was not allowed to sharpen tools, so I'm not sure. <g>
We had a 1924 Taft surface grinder that had been dedicated to that use, and we had several tool-grinding fixtures for it. I just scrapped that grinder a few weeks ago, but I never had the fixtures for it.

Iggy should make some more inquiries and decide how far he wants to go. Drill-grinding fixtures are common and shouldn't give him much trouble. Handling end mills on a bench grinder sounds like trouble without a sophisticated fixture, like a Quorn.
Given that he's active in the used-machine market, he may want to scrounge up a real tool grinding machine. Those things are complex and, new, they're very expensive. But I've never looked for one on the used machine market. It could be cheaper and easier for him in the long run -- if he has room for it.
--
Ed Huntress



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Brierley drill grinders show up on ebay from time to time, they go fairly cheap. The one i bought back in 2003 cost me $99.51.
Best Regards Tom.
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I realized that I could grind a drill bit in the end mill fixture, set for back relief like this:
http://travers.com/images/Items/500x500/85-090-001ill2.jpg
The drill bit passes through the hollow closer nut and over the side of the mag chuck. I need it only for S&D bits larger than 3/4" since the 3/4" Darex collet works in the 1/2" Drill Doctor.
jsw
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wrote in message

So do you grind a flat, angled relief that way? Or do you rotate the bit somehow and generate a curved relief?
--
Ed Huntress



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I think the relief has to be flat, and narrowed by hand-grinding the back relief. End mills drill well enough with a narrow flat relief. I rough out slots by plunging to avoid dulling the edge flutes which are harder for me to resharpen.
I suspect they will be good enough for controlled machine drilling but might dig in excessively freehand.
jsw
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wrote in message

Types of drill bit relief have actually been studied, but I haven't looked at that stuff for around 30 years. Somewhere I even wrote an article about points and reliefs for production drilling, and it was a pretty long one.
I'm beginning to hate getting old. d8-)
--
Ed Huntress



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On Sat, 4 Jun 2011 19:25:29 -0400, "Ed Huntress"

I've got the silicon carbide on one side set at about 10 degrees for ruffing and secondary relief. Then the diamond wheel on the other side at about 5 degrees for that very fine cutting edge. Werks grate for carbide this way.
I've never looked, but a CBN for HSS would be a very nice addition. I assume its made.
Karl
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I've seen CBN for surface grinders but I don't recall seeing a CBN wheel for a bench grinder. The ones for surface grinders are pretty darned expensive.
--
Ed Huntress



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I use one in my end mill sharpener but it's a cup with a ring of grit attached to it, basically the same construction as with most diamond wheels.
--




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For fixture-held drill sharpening, there are numerous devices which can be added/bolted/clamped to most common grinders.
Look into 4-facet resharpening.. the only 2 facets that are important are the 2 primary facets (one on each flute), which assure centering and proper relief, while the secondary facets only determine the width/thickness of the cutting faces.
Generally, all holders require adjustment (or anticipation of) the proper finished location(s) of the final grinds. That means when material is removed from the tip, the orientation of the twist needs to follow. As more material is removed without rotating the drill, the cutting edges are established at the wrong place in the rotational relationship to the flutes.
Only a couple of resharpening machines are designed to follow the twist as the material is removed.. other more common (add-on) fixtures require a fixed setting of the twist for a specific amount of material removal, and after that much is removed, the drill needs to be rotated. For more material removal (chipped flute for example) the operator may freehand the rough shape to remove the damage, then rely on the accurate fixture settings to apply the proper centering and relief.
Some handy machines and add-ons:
Black Diamond Darex General/Craftsman copy Kaindl Kalamazoo Viel
Many precision resharpeners don't require using the side of a grinding wheel, in that the geometry of the fixture utilizes it's precisely-placed motion axes to use the dressed/flat edge of a wheel (or even a belt sander's abrasive path, such as the Viel for HSS drills).
As I've stated numerous times in the past, it's relatively easy to make center cutting split-points on common twist drills. The back side of the flute material is removed first, followed by any of the common methods used for point finishing. Split-point grinding isn't a delicate gashing operation which most folks think it is.
The benefit of split points are numerous.. they begin cutting as soon as they contact a surface and continue to cut for the entire operation. Conventionally ground common points require continuously applied power and pressure to displace the workpiece material in the area of the chisel edge present in the web area.
Split-point drills are widely accepted as being much less prone to wandering upon contact with the work surface, but they also make much more efficient use of time and energy.
--
WB
.........


"Ignoramus5230" <ignoramus5230@NOSPAM.5230.invalid> wrote in message
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ACK.. I was using "flute" (no metal area) for land (or flank) in the previous post.
--
WB
.........


> Look into 4-facet resharpening.. the only 2 facets that are important are
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On Sat, 04 Jun 2011 17:50:34 -0500, Ignoramus5230

It is pretty much a one purpose machine - to sharpen single point tools.
If your carbide drills are "concrete drills" the inserts are sharpened by grinding an angle on them. A twist drill, on the other hand, the other hand are sharpened with a curve. for a concrete drill you could adjust the table for the correct angle and just hold the drill with the cutting edge horizontal and push it straight into the wheel.... or use a pedestal grinder.
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