Problems with Drill Doctor solved
Rather than hijacking a thread running here on the Darex I thought it better to start a new thread. This may be common knowledge but I hadn't seen anything about it, nor did the Darex rep know anything about it when I spoke to him at a show.
I have a 750x and like the split point facilities. When I first got the machine it worked like a charm, sure it's not industrial quality by a long shot, but I couldn't understand what all the bad reports were about. If treated gently I couldn't foresee any problems with it lasting a while and doing a reasonable job.
Soon thereafter the drills started being ground with negative relief and clearly didn't cut. Nevertheless the (incorrect) relief was symmetrical on both sides. Changing the "notch" the collet was sitting in helped a little, but something clearly wasn't right. I couldn't work it out as the only possible explanation was that the drill was rotated when it was ground. When I looked at it carefully I could see the "prongs" that are used to align the drill in the collet were gripping part of the shank of the drill that had been ground from splitting the point instead of the flutes as it should. There's not a lot in it, as it only JUST grips the wrong part. As predicted, it allowed the drill to be rotated within the collet. Whether that would be a problem to others may depend on the depth of cut set by the stop, I have mine set to just skim a little off each time I grind. It's clearly a design fault, as if the "prongs" gripped further up the shank the problem wouldn't occur.
In practice I've found the solution is to keep a finger on the end of the drill and use my finger tip to manually rotate the drill to ensure the collet is gripped at the correct angle. If anyone is having problems with a DD not grinding drills correctly this could be something to look into.
Hope that's of some use.
The main problem I have seen is the fact that the alignment "prongs" seem to be made from old pieces of pallet strap that they must have cut off a shipment...... Not very sturdy, and seem to have shifted or worn.
That. and the fact that they ONLY work on "normal twist" . If the drill has ANY other twist than the "normal one" that the DD expects, it won't work.
Mine cannot possibly be gripping on the split, since I never USE the split.
Also, it grips the drill well back from the tip, at least a quarter inch, maybe more. Always has, so that hasn't changed. If the twist is different than expected, the tip will be at some angle other than expected.
As far as the split............... The collets are so loose in the tube on mine that the end of a smaller drill moves around a distance equal to about its diameter.... So when I try to split, I either get a split past the center, or it leaves a little square piece of the point in place. Getting a good split is not possible unless you are remarkably lucky.
I assume some of the other problems are also due to the sloppy fit of collets in the tube, but I have not spent the money to buy a new tube. I don't expect it would fix it, they SWORE that the collets were the problem, and sent me more, but there was zero difference.
G'day Jerry, I'm just relating what I found on my machine, other's milage may be different of may have a different set of problems. My machine is quite new, and I was sharpening the same bunch of drills when it suddenly started developing "problems", nothing else had changed. In hindsight I realise that initially I wasn't splitting the point, next sharpening when I started splitting the point on some drill was also ok, since one sharpens THEN splits the point. It was only when I went back and tried to sharpen with a point already split that I started seeing problems. Being new it's possible that the collet problems have been fixed as I certainly couldn't fault that.
I agree, the prongs are pretty miserable. I haven't seen any wear in the machine as yet but don't doubt it will occur. Just the same I think the market is very much pitched towards the occasional versus professional user and the price was certainly right. I bought mine from Enco and simply run mine on a step-down transformer. As I recall it was somewhere around US$150 on special, which I think is very reasonable. Here in Australia you can expect to pay more like US$400 for the same unit (except it runs on 230V). I doubt it's worth that. The next step up was a Taiwanese drill sharpener at around US$1000 here, a BIG difference from the $150.
A mate of mine says, "why bother, just throw away the bit". That's all very well, but firstly I find that good quality bits aren't cheap, even in sizes I'd use a lot of (3-8 mm). More the point is that invariable one doesn't throw the bit out and continues to use it even when it's quite blunt. Now days at the first sign the bits are getting dull I'll pop them in the DD and just touch them up which has made the whole process a heck of a lot more pleasant. EVENTUALLY I'll possibly go to a professional drill sharpening machine, even though in all honestly I really can't justify it. Even though the problem with my DD seems to be sorted, I still don't think it grinds as well as the factory grinds on new bits.
I'm with you on that... I don't like the point that much either, but I have a couple bins of dull drills, and had a fine time filling up the drill indexes.... until one day it didn't work right anymore.
Originally Posted by PeteF
The DD point does not seem to cut as freely as the factory point. And for sure, I have not ground enough off to get in trouble with needing point thinning.
I really want to do a good 4 or 6 flat split point, and the DD isn't ever going to do that. More stuff for the list.....
I have a 750 DD and after trying every conceivable bit of advice to make the thing work right I have decided it is a total POS and can never live up to it's claims! A total waste of money IMO.
How much will you sell it for?
Originally Posted by radkins
My model 500 works for me, but then I am only a less than rich farmer. I didn't want to say poor farmer or someone would think I didn't care about how well a farmer I was. Not a real Machinist.
I've had the old style 3/4" DD for over 15 years, sharpened a bunch of bits with it, and have never been disappointed with it's performance.
The people who are mfg it now are also easy to deal with. The jaws broke in one of my drill holders, last year, and they sent a replacement "no charge".
People say I'm getting crankier as I get older. That's not it. I just find I enjoy annoying people a lot more now. Especially younger people!!!
Huh, I wonder why? The actual mechanics are pretty simple, have you taken a good look at why? It's interesting how for precisely the same machine (I presume) some people report reasonably good success, others reckon it's absolutely hopeless.
Originally Posted by J Tiers
The thing I like about the split point is the fact I can often take the finished size drill and bring it straight down on the punch mark, or for even rougher work where accuracy isn't a huge factor, straight down at a mark and have it start cleanly and without wandering all over the place. A big time saver.
I can't recall it being covered in HSM, but MEW had some excellent articles a couple of years back covering the theory, jigs and simple rests that allow multi-facet sharpening. If George hasn't covered it in recent times I think it would be of interest to readers. If you're keen to pursue that avenue in the meanwhile I can search back through my back issues and you should be able to order the appropriate issues to construct the appropriate bits 'n' pieces.
"Precisely the same machine"
That's where I reckon the problem is. I mentioned that mine has at least 3 or 4mm shake of the drill point. No special wear, no broken pieces, no good reason for it. Not many report that, but perhaps they have not popped off that little cover over the wheel and looked. Dunno.
I have no doubt that the problem is the molding of the fiber-filled plastic pieces may vary, etc. The folks at DD mentioned that my particular date code range "was one of the best"......
For the life of me I can't imagine why a product made of molded (precisely molded, we presume) parts would vary by lot. If it was carved, the ones made by "old Walter" might be the best, but with molded parts, they all ought to be far more alike than peas in a pod, and with any sort of QC, they all ought to work the same...... but apparently they do not.
When you're grinding the bit moves around 3-4mm at the wheel? Yeah well that would do it! The way the collet is rotated and also rocked it's possibly a bit deceiving, but I think mine is quite solid in that regard, but will pay particular attention next time.
The splitting is however a bit of a lucky dip. It has to be absolutely spot on to get a good split. generally speaking it is, but I've also had a few duds ... though come to think of it as I write, there's a good chance they were also the ones that didn't grind correctly