Thread: Drill Sharpener

Hi guys, Does anyone have an opinion on these sharpeners?

http://www.ebay.com.au/itm/Drill-Doc...0342cb4&_uhb=1

And do split point drills centre noticeably better?
$_57.JPG

Hi Rocket man,

I'll probably get shot down in flames here but I bought the Dril Doc 750 a couple years ago. I found that I did not have the required skills to sharpen my twist drills to any level of accuracy. It was also a skill that I did not want to spend too much time on so I bought the DD. It's probably the dearer of the cheap end of drill sharpeners (or the cheapest of the better, whatever way to look at it) I cannot fault it. It will reliably sharpen 2.5mm all the way to 19mm. It can also grind in the split point and has the ability to sharpen carbide masonry drills and spade bits. The only thing that seems to require a bit of a play is the drill point relief. Some of my first attempts did not have enough relief and so did not drill. I used the default setting but I had to redo it on the next notch.

If you have no other way of sharpening your drills and, like me you were a bit hit and miss with sharpening then the DD should do the job nicely. I dare say that a t & c grinder (with the required parts) will still produce a superior edge than the DD though. There will be people here that will say that drill sharpening is an important facet of machining and metalwork that should be learnt AND mastered. Each to their own.

Simon

I've got one but a,
I'm not that impressed with it for the price. To start off with I used it a lot - thinking I'd get used to it and make more consistent angles and sharpness. But I have to admit I find the plastic construction not rigid enough - you can easily make two different flutes because it caqn flex in the hinge of the mechanism. Gone back to the old sharpener like this one:
http://www.ebay.com.au/itm/131222579172
or sharpening off-hand....

Originally Posted by GSRocket

Hi guys, Does anyone have an opinion on these sharpeners?

http://www.ebay.com.au/itm/Drill-Doc...0342cb4&_uhb=1

And do split point drills centre noticeably better?
$_57.JPG

I bought a model 750 about a year ago. But I have not tried it yet. Still have enough sharp Drill bits in stock, either new or previously resharpened with the swinging type jig that everybody uses. So I cannot tell you yet how well it works. Once I feel the bin with blunt drills is full and I have some idle time, I shall give it a go.

But I can tell you how to save quite bit of money when buying a Drill Doctor. Buy it from Amazon. Shipping from the US is by Amazon, very well packed, fast and very affordable. I paid US$ 133 for the DD750X, and $29 for shipping, all up $162. About half as much as it costs here in Australia. There is only one caveat, it will be a 110V model. Now I had a suitable step down transformers for free at hand, just had to spend an extra $20 for a nice enclosure. A 300W step down transformer can also be bought locally for cheap. The Drill Doctor uses a Chinese DC type motor hooked up to the line cord through a small bridge rectifier.


PS: yes, split point drills are easier to center, and also need much less downforce when drilling a plain (not pre-drilled) hole.

Yes I have this model and agree with the comments by Simon.

I've never had an issue with the plastic construction and if used with common sense I feel it is adequate for home shop use. It's very quick to use and will encourage drills to be sharpened when dull instead of persisting with blunt bits.

The only issue I've come up against is the lack of clearance as noted by Simon. This will vary depending on the helix of the drills you use, so may need a little experimentation. Once it's resolved the drill bits are symetrically ground and will drill accurately.

Likewise I bought mine from Enco in the US when it was on special, but does of course require a step down transformer.

Provided it's realised that you're buying a machine aimed at the serious end of the hobby market, and won't stand up to sustained professional use, I'd have no hesitation in recommending the sharpener.

A split point is meant to lessen the amount of "chisel" in the middle of the drill. By reducing this the drill is meant to cut more easily and require less force (the chisel part rubs more than it cuts, hence the use of pilot holes to make drilling easier).

As for you Simon -

(actually, I just wanted the chance to use the smiley)
One of the things I learnt about sharpening drills off hand was after looking at an early Darex sharpener. It's a more complex motion than you first think because as well as rotating the drill around it's axis at the right angle to the wheel you also have to slew it off to the left to relieve the cutting edge. Without this my drills would just rub and not cut properly. After seeing the cam action Darex used I realised my error and now get much better results. It's easiest to learn this technique when someone shows you - perhaps if you attend Scrapefest 14 as cook and bottle washer, one of others may be able to show you. Failing that, drop around some time...

Michael

I've had a locally bought 750 for a few years, its definitely not an industrial quality machine but is OK for home workshop use. Its not foolproof, the main thing I've learned is that (generally) to get the proper point geometry you need to set the drill for minimum contact with the wheel.

Prices for the 240V Drill Doctors are outrageous, if I need another one I will buy a US voltage item and run it through a transformer.

If as cba says the motor is a DC item, does anyone here have the electrical smarts to say if these are actually a universal 110/240V item, (much like most computer equipment for instance) and the makers put different voltage stickers on them for different markets?

Originally Posted by Michael G

As for you Simon -

It's easiest to learn this technique when someone shows you - perhaps if you attend Scrapefest 14 as cook and bottle washer, one of others may be able to show you. Failing that, drop around some time...

Michael

Hi Simon,
As I will be attending Scrapefest 14, it will be my pleasure to show you how to freehand sharpen a drill bit.
I'll even show you a trick on how to get the angle (118 deg) roughly if the drill has been snapped in half.
This skill comes in handy if ever you need to sharpen a drill while there is a power outage

Phil

Thanks guys you have been very helpful, as usual.
Once upon a time I could sharpen drills freehand rather easily but the lost the skill somewhere never to be found again
I did notice too that they are much cheaper in the States so I'll do what cba did.
It really goes against my grain to do that but the price difference is so significant it's makes you wonder
but it does seem to be a common problem right across every interest and industry.

It would be handy if anyone knows the answer to Bobs question.

If as cba says the motor is a DC item, does anyone here have the electrical smarts to say if these are actually a universal 110/240V item, (much like most computer equipment for instance) and the makers put different voltage stickers on them for different markets?

Hi all,

Thanks Michael for the offer. Who knows, I may hold you to that!

Hi Phil, looks like you got yourself a task at hand come scrape fest! Actually, I have kinda sold myself a little short. I have successfully sharpened drills in the past but I am very hit and miss with it. Some I have sharpened and they cut straight and like cutting through butter, others were a dismal attempt!

I also have a confession. I too bought my DD from the US. It was about half the price delivered! There is no way I would have bought one here for full price. Same same as other have noted, you do need to consider it will be 110V which I was expecting. It just so happened I had a suitable step down transformer from an old treadmill. I didn't mention this in the previous post as I thought I may have been the only tight wad to do stuff like that! Turns out I'm in good company . I also looked into swapping the motor. It's a DC motor and I even managed to source the brand and model of motor but in all honesty, if you go to all that trouble then you may as well buy one here. So, I just made a dedicated 110V power supply on an MDF board.

20140626_081456.jpg

OK. what the go with my pics. Does not matter which way I orientate them before I post, they always end up like this! Then I get people complaining about sore necks!

Simon

[QUOTE=cba_melbourne;1785815 The Drill Doctor uses a Chinese DC type motor hooked up to the line cord through a small bridge rectifier.


[/QUOTE]

Thats interesting...I dont recall seeing a rectifier in mine when I pulled it apart to lubricate the bearings...they went a tad dry

Originally Posted by eskimo

Thats interesting...I dont recall seeing a rectifier in mine when I pulled it apart to lubricate the bearings...they went a tad dry

This site shows the 750x innards, there is also a pic that shows you the motor nameplate. The rectifier is needed, because this is a very low cost permanent magnet motor. Not a universal motor, which would have a field winding instead of the magnets: http://screwdrivers.viabloga.com/new...20v-convertion

If one goes to the FAQ at the Drill Doctor website, they will claim that you loose warranty if you use it with a step down transforemer, because you then feed 50Hz instead of 60Hz and that would - they claim - overheat the motor. I cannot see that happen, I actually cannot see their problem. The rectifier bridge transforms 120VAC/60Hz into pulsating 120VDC/120Hz, after a 240/120 step down transformer into 120VAC/100Hz. Without there being a filter capacitor, the only difference is 100Hz vs 120Hz, with the same sinusoidal shape. I think the real reason is, that they would like to make a higher profit with the 230V version.


By the way, Amazon also sells the two different spare diamond wheels (180 grit and 100 grit) for USD 19 and 21. The coarse wheel is intended for larger diameter drills where more material needs to be removed when sharpening the first time.

Regarding the freehand grinding of drills, my experience is the larger the diameter the easier this is. I never had much luck at getting both lips exactly the same length with drills less than 12mm diameter. And then, with the two lips slightly different the drill will cut oversize. It would not matter on many jobs.... but I do not like to have too many drill sets sitting around, one only for brass, one only for steel and accurate sizes, one with Cobalt drills, one for plastics, one for general use drilling oversize, one for.... The cheap freehand jig depicted by Jhovel works much better than freehand, but I found it very time consuming to setup, mostly because it is a very sloppy and inaccurate construction.


EDIT: it could also be that they sell the 230V version dearer, in an attempt to recover the extra cost for the electrical safety testing to IEC standards. After all, the export model has to deal with twice the voltage internally. But that is irrelevant if we use a step down transformer.

Good points Chris, the fact that any mains powered appliance sold in Australia requires testing and approval is a considerable cost to importers and of course this needs to be passed on. Nevertheless there really is a very significant price differential and it's a bitter pill to swallow for those opening their wallets here. I've never seen the inside of a DD, and now I have it makes me believe they really are quite expensive for what they are. The "secret" to the machine is in fact in the collet and the cam arrangement and from what I've seen it's a reasonably consistent design throughout the Darex range, with the commercial versions simply of heavier duty construction. If I recall correctly they were even more expensive than this in the past, but I may be mistaken.

With regard hand grinding drill bits, nothing personal to anyone, but I do wish this wasn't raised every time somebody asks for help regarding a drill grinding machine. This has been covered countless times before and nothing has changed. Most of the time holes are drilled for clearance, and drilling oversize holes really doesn't matter. That being the case, by all means learn how to grind a drill freehand,, it's a very useful skill and if no particular precision is required will be more than adequate and save the expense of buying a machine. On the other hand, don't do so under any illusion that the bits ground are as accurate as will come off a machine, even a basic machine such as this. They're not, it's been proven countless times in both formal and informal studies, hence why machines (often very expensive ones) are used in high volume production environments. Know it, accept it, and move on. It's not to detract from that skill, just a fact of the matter. It's no different to, say aviation where pilots use both an autopilot and hand fly the aircraft. Nobody is under any illusion that they can fly more accurately than the autopilot, humans can't, egos are stowed, that fact is accepted and each mode is used as appropriate to get on with the job.

Originally Posted by cba_melbourne

This site shows the 750x innards, there is also a pic that shows you the motor nameplate. The rectifier is needed, because this is a very low cost permanent magnet motor. Not a universal motor, which would have a field winding instead of the magnets: http://screwdrivers.viabloga.com/new...20v-convertion

I am not disagreeing with you ...its just that I honestly cannot recall seeing it

I would except the argumentation of higher voltage/testing ect, except the price problem is right across the board.

It's coming up throw out week here, so there should be few tread mills available
Are there any other appliances should I keep an eye out for?
I take it that voltage step down is the steel chunk to the left of the switch?