Author Topic: Getting the most out of a drill grinding jig, or Perfect twist drills every time  (Read 19505 times)

Offline Graham Meek

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Hi Baron,

Get them they will appreciate in value shortly.

Hi Thor,

The Picador pivot is vertical, the clones can lean any where from 6 Deg to 13 Deg, a lot depends on what era they are from, the newer jigs tend to be 13 where they should be to conform to L. A. Van Royen's  Twist drill grinding jig, which is what I based my modifications on.

My best regards
Gray,

Offline Graham Meek

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Sorry I have been absent for a while, I have been busy writing. I have attached a couple of up-close photographs showing nearly the full range of drills ground to date, the only one missing is the 1" Blacksmiths drill shown originally in the opening set of photographs. The smaller drills below 3mm or 1/8" diameter require a special holder and an alignment jig, purely because I have not the necessary number of hands required to carry out all the adjustments and hold the magnifying glass to see the drill lips.

My best regards
Gray,

Offline Baron

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Hi Gray,

Bugger !  Some one has beaten me to those drill jigs...  Ah well you can't win them all :)

Best Regards:  Baron.

I donít regret the things Iíve done, I regret the things I didnít do when I had the chance.

Offline Graham Meek

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Hi Baron,

The word must be out, old drill grinding jigs shortly will be like "Hen's Teeth".

My best regards
Gray,

Offline Steam Haulage

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Thoughts of my old tools prompted me to search for a Picador. Guess who's been lucky. ;D
It just needs a clean-up perhaps following Graham's improvements.

Jerry
Dogs look up to you, cats look down on you, pigs treat you as equal.

Offline Graham Meek

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Hi Jerry,

The value of these units is going through the roof. I saw a genuine used Picador one on a trade stand at Bristol in August and the price tag was £38, I paid less than £5 for my used Far Eastern not so good copy of a Picador from a car boot sale.

Since writing this post I have written an overview of the modifications and this has been published here,

http://www.modelengineeringwebsite.com/Drill_grinding_jig_1.html

The more in-depth technical article with drawings has been sent to Engineering in Miniature, when this will be published I cannot say as I understand Editorial changes are taking place at Tee Publishing at the moment.

My best regards
Gray,


Offline Steam Haulage

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Hi Graham,
Thank you for your link. Having read the information and looked at the pictures I suspect my Picador may be one of the very original versions, it looks surprisingly like the one I bought in Sarjents over 30 years ago. (Happy Days  :DrinkPint:)
This has slotted screws rather than PK, Phillips or Posidrive. Additionally the nameplate has the raised lettering infilled with blue.
For such an early unit it is in surprisingly good condition with hardly any marks on any of the mating parts, except on the square bar where the and screw as caused an indentation by being over tightened. Even the box is in good nick, although the staples have rusted and stained the cardboard.
I'm looking forward to trying to get the unmodified version working in the fashion set out on the instructions on the yellow label stuck to the box lid before I do any modifications, following your method.
Jerry
Dogs look up to you, cats look down on you, pigs treat you as equal.

Offline Graham Meek

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Hi Jerry,

I was given a Picador many years ago, I have used it mainly to regrind, the neighbours and my relations drills which seem to come by the sack full. I have always had good results with that unit, it is streets ahead of the reproductions. The only downside is the amount of offset built into the jig because the jig is being asked to grind so many angles, but I am sure you will be happy with the results.

My best regards
Gray,

Offline Mosey

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We have that identical drill grinding gadget over her in the US, only it has a Sears Craftsmen 9-6677 label on it. If anyone wants mine, it's free if you pay the shipping cost. I bought a Darex drill grinder and find I have no use for this problematic tool. I don't like it at all.
Mosey  :ThumbsDown:

Offline Lew Hartswick

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Remembering this thread and we just found a General Model 825 in a cabinet at school that looks
exactly like one of the above pictures of a Picador. The rotation axis is tilted at about 8 deg as close
as I can tell measured with a long 3/8 rod in the base and protractor head on a "square".  It looks like it
would do a decent job with bits from 1/2 down to maybe 3/16 or so. 
  SO!  I have a "Plan"  :-)   How about building a scaled up version to handle both Silver & Deming bits
up to 1-1/2 " and taper shank ones up to the largest we have 1-3/32 by 12" long.  :-)  The big/only
problem will be the grinder to use.  No way to hang this sort of thing on either of the Baldor bench
grinders we have.. I'm "thinking" about some sort of steel base that could be held on the mag chuck
and using the surface grinder.    Any comments on this part of the plan????
 The "fit and finish" of the as cast assembly of the General leaves me a bit or more than a bit un-happy.
Pinching a 3/8 steel shaft between a thin spring steel flat and the as cast Aluminum V of the base just
begs for something more sophisticated. :-)
 There are, in the wood shop 3,  12" disc sanders. Any one with experience using one of these with
?some sort of PSA disc of what material and grit to grind normal drill bits?????
 To handle the 12" long taper shank bits the fixture is going to pretty big and heavy so a major support
structure is envisioned.
  If it comes about pictures and sketches will be forthcoming. :-)
   ...lew...

Offline Graham Meek

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Hi Lew,

In the modifications I made to the existing drill jig by adding Bright Mild Steel angle to the drill rest, the additional rest and a longer adjustment bar, the as modified the jig will comfortably take 1.500" diameter taper shank drills.

Yes the 3/8" pivot is a bit of a problem area that is why I added another piece of BMS angle here to take a larger eccentric pivot bearing that allows the large offset of the original design to be varied to suit each drill size.

I would not be without my modified unit now, and all it cost me was some time which I hopefully have plenty of and the price of a decent cup of coffee, (the materials came from the scrap-box).

My best regards
Gray,

Arbalest

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Some interesting stuff here as well:

http://www.gadgetbuilder.com/DrillSharp.html

Given the popularity of ER32 collets I'd really like to see someone build a jig using them.

Offline Graham Meek

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Yes John wrote an article in HSM some months back now on the construction of this useful tool. Because I have limited space in my workshop, if I am pushed for a 4 or 6 facet drill I usually use my 2/3rd's full size Quorn to accomplish the task. I also use the Quorn to regrind the split point drills that I have in conjunction with the drill sharpening jig.

My best regards
Gray,

Offline Graham Meek

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For those who may want the words and drawings on how to modify one of the jigs, or should anyone come to this post in the future, the article starts in the March 2016 issue of Engineering in Miniature.

My best regards
Gray,

Offline Bjorn_B

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Not wanting to hijack this thread, it inspired me a lot.

But, if anyone can explain the thoughts behind the geometry of this commercial variant of a drill sharpeing fixture... To me the geometry is totaly the other way round... We have one of theese at work, will try to sharpen my lager morse taper drills in this, wonder what the outcome will be..