Resharpening Drills Any Experience with TDR SRD Drill Grinder ?

The topic of drill sharpening gets brought up here in RCM on a fairly regular basis, when cheap and expensive drill sharpening fixtures or dedicated drill sharpening machines often get discussed, but I don't recall the TDR SRD machines being mentioned any time recently.

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I'd watched a couple of these sell on eBay over the last several months, and I was outbid twice, but I wasn't trying very aggressively to get one.

The unique "chuck" used to hold the drills keeps drills of various sizes centered so that no adjustments need to be made when changing to another size (1/16" to 13/16" according to the manufacturer's claim, larger sizes with optional accessories).

The "chuck" that's used to hold the drills is unique square block that consists of two halves, which are two mating segmented V blocks which mesh/interlace to form a square opening where the drills are secured, essentially making a self-centering 4-jaw chuck. The centering aspect of the V blocks maintain the correct center height. The square outside dimension ensures that the two grinding positions are oriented 180 degrees apart.

Another part to be noticed is the small, straight cup wheel. A chamfered or beveled face on the *inside* edge of the wheel is where the drill point contacts the wheel. No separate additional motion is required to crown the cutting face of the drill flute. The precise orientation of the drill's centerline, in relation to the centerline of the cup wheel, and the feed angle of the sliding assembly, determine the relief angle of the drill point. A separate adjustment sets the overall inluded angle of the drill point.

The motor travel remains stationary for the most part, and the chuck holding the drill moves the drill point across the inside beveled face of the wheel on a lubricated, free-moving slide assembly (motion supplied by operator's hands).

There is an adjustment screw in the wedge-shaped control block/chuck holder for setting the drill cutting edge relief angle.

Most of the motion during resharpening is the slide. When one side of the drill is completed, the chuck is rotated (rolled over) 180 degrees, and the other side of the drill is ground. The unique chuck maintains the proper center height to grind the second cutting edge.

The motor may require a slight amount of inward adjustment during the resharpening, but otherwise it doesn't travel during sharpening. Unless the drill point is badly damaged, the motor probably won't need to be repositioned repeatedly to complete the resharpening of both drill cutting edges.

It appears that there would be a little difficulty at first, in getting familiar with the proper positioning of the web and cutting edge. The manual describes how the cutting edge is lined up with a scribed mark on the chuck, but some experience will be required to get the rotational position consistently correct, it seems.

One noticeable advantage would be that the drill point is facing the operator, so examining the drill point geometry while resharpening is fairly easy.

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I bought one early last year off eBay. My beefs have nothing to do with TDR, but rather with Reliable Tool's description that it ran fine and was in good shape.

When I turned it on, the motor ran, but sorta moaned and I could see it was throwing sparks halfway around the commutator. Motor was basically thrashed. I got a partial refund based on having to replace the motor. Just short of ordering one from TDR, I realized I had a nearly identical Bodine from an old lapidary setup. Had to thread the end of the shaft for the stones, but it was a free upgrade to 1/4hp from the stock 1/8hp.

Also, the chuck was badly worn. I spent an hour working it over and got it cleaned up enough to give it a try. I was impressed with the ease of sharpening. Bought a new chuck from TDR, and it naturally did an even better job. Adjusting for point angle and lip clearance is a breeze. I was not exactly thrilled that there was nothing to indicate just how much lip angle the height adjustment would give until I received some literature from TDR and realized the chuck rest was supposed to have marks. The anodize was worn enough they were not visible. I'm going to upgrade to allow sharpening reamers, which will solve that problem.

First drill sharpener I ever used was a Black Diamond, and it was the standard I'd always dreamed of owning. But I am really impressed with the results from my SRD. I can't exactly explain it, but drills often don't 'look right' after sharpening compared to the OEM grind. But then, I've yet to have a drill wobble upon initial entry. Everything I've sharpened so far drills very very nice clean holes that are to size. I also like the small footprint.

It was worth the frustration of dealing with a badly worn unit, I'd just advise taking care to try and judge condition and make sure you get a good one up front. Folks at TDR are very nice and really know their product.


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Jon Anderson

Thanks for your comments, Jon, they're very much appreciated. I just bought a model 80M, cheap, but with no chuck/drill holder. Buying a new chuck from the maker appears to be the best option.

I'm hoping that small drills under .250" can be sharpened by placing them in a pin vise, and then holding the pin vise in the chuck, maybe.

Greedy eBay sellers will say anything they think might get them another dollar.. I've had the same experiences.

This 80M unit has a Bodine 1/4 HP 5000 RPM ball bearing universal motor, and I was just checking the brushes and bearings when I noticed your reply.

The motors on newer models are stated to be Baldor (TEFC PM, I think) motors.

Cheers on having a spare motor.. it seems that one can never have too many, and it's hard for me to pass up a decent motor any time I see one for sale.

In case you aren't sure about the location of the marks on the control block, there are three marks for adjustment..

C - 12:00 position B - 06:30 A - 05:30

BTW, manuals are available for 3 models at the Download Manuals link on the drill grinder site.

I've used Black Diamond and other expensive sharpeners, and they usually have a large inventory of collets and accessories. The TDR SRD sharpeners eliminate the need for all those extra parts (and cost/storage/care of them).

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I meant to say that I'm hoping that small drills under 1/16" .0625" can be sharpened by placing them in a pin vise...

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I think the main problem with small drills is not holding them but getting them oriented properly. The gaging devices used do not seem to work well with the small flutes. All the sharpeners depend on the correct length and rotary position of the tip to create the correct profile.

Don Young

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Don Young

You're definitely right about orientation being a problem, Don. The advantage the TDR SRD grinder has, is that the drill point is facing the operator, unlike most drill sharpeners where the point can't be observed until the drill is removed.

Being able to see the drill point, and seeing the web are two very different things for many folks including myself, so I intend to see if I an rig up an optical device with a working distance of about 4" to be able to see the point geometry.

With the TDR SRD grinder, getting the first flute ground correctly is all that's required (if everything else is positioned properly), beause the second flute will be a duplicate of the first.

I recently got a couple of #80 drills (with a small drill press I bought), and I don't expect to be resharpening them.. but I have quite a few dull drills under 1/16" that I would attempt to resharpen if I would be able to align them properly.

Tiny drills can usually be resharpened with a hand stone if one has an optcial device to be able to see the point. There is so little area involved that a 2 or 4 facet point will generally be suitable.

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