Thread: GMF drill sharpener attachment

Originally Posted by Anorak Bob

Sorry Bob,

I would have piped up earlier but I've been dragging myself around the naval museum here in Istanbul. I have a complete GMF drill sharpening attachment at home. I'll be home in a week.

Bob.

Cheers Bob, looking forward to swapping Scrapefest stories to.

Did you go to the big military museum in the centre of town. That's where I attended a conference last year.
Even though the conference venue was right next to the conference venue I was too tired to go in and take a look.

Originally Posted by BobL

Thanks for that.


I understand the blue text but not the green text


Yes please.

Graham Meek Offset Check.jpg

As I printed the pictures on a mono laser, that is all we get. This picture shows the checking of the built-in offset. It is a bit difficult to tell what the centre in the drill chuck is pointing at. I have highlighted the edge of the drill holder. This is the angle piece. The left edge as we look at it is highlighted. The centre is pointing somewhere in the middle of the angle. About 6mm off to the right of the angle centre line actually.

My Jig Showing Offset.jpg

This is my jig depicting the offset. The blue line is the vertical pivot axis. The green line is the drill bit pivot axis. This is just showing the centre line of the drill bit. The top pic is one way to check this. Black line shows the difference per red arrow. The black arrow points to the edge highlighted in black above.

Graham Meek Cutting Angle Check.jpg

From the start of the process. Checking the grinding angle. There is a tapered ali block underneath to correct the untrue angle. There were posts mentioning numerous different results for this check including one that was spot on. Mine is 88 deg. It should of course be 90 deg.

Graham Meek Eccentric Bush.jpg

This shows the eccentric bush in position. It is actually 2 pieces. The top piece with the clamping screw sits inside the lower piece with the biggish chamfer and pivots in this piece when the work is carried out. I may be wrong on the details here. The top piece is drilled/bored 6mm eccentric to compensate for the offset measured above. Some of this offset can be applied as needed depending on drill size. Drill Diam/13. Marks have been scribed for various sizes. The jig shaft is rotated to position when applying this offset and then clamped with the allen head screw shown.

Graham Meek Angle Drawing.jpg

Dean

Graham Meek Drill Movement Detail.jpg

Details of the drill movement system. The drill bit should be set just touching the edge of the grinding wheel by moving the whole jig base which is then tightened in position. Any feed of the driil bit into the wheel is done with the mechanism pictured. It is almost identical to what I have used for years except I still have the original plastic wheels while Graham replaced these with ali versions. The locking nut/wheel is very similar to mine which was just one I found. These jigs do not come with a locking nut like this. They rely on a spring inside the top wheel. I found this did not hold the adjustment position.

For those that do not know how these work, the rear wheel and lock nut sets the final grinding position for the drill. A simple stop. The upper wheel is used to gradually approach this position. When you reach the stop the drill is turned around to grind the other side after backing off from the stop position of course. If there is a lot to be removed, I do this again in a finishing step. I often found that when I got to the finish position on the second side the stop had moved. That is why I use a lock nut.

Graham Meek Rotation Stop.jpg

This shows Grahams design for the flute stop which sets the position of the drill axially. The drill bit should have the cutting edge vertical. When the drill is fed inwards for grinding, the flute rests against the flute stop (with help sometimes) so the drill rotates to remain in position with the cutting edge vertical. This is why the base is not moved after the initial setting. This picture and the next one, the finished product, show redesigned clamping methods.

Graham Meek Finished.jpg

Dean

Hi Bob,

The attached photo from an old thread shows a glimpse of the feed device absent on yours. Should be easy enough to replicate.



I didn't know about the military museum. I plan to visit Istanbul's industrial museum tomorrow - http://www.rmk-museum.org.tr/english/exhibit/index.html while Vicki checks out the Topkapi Palace. I will forego the Blue Mosque to visit the military museum.

BT

Just thought I would post a couple pics of my set up of the same attatchment.

Matthew has the missing adjuster. Here it is in a bit more detail.

BT

GMF Drill Sharpener Feed Adjuster 001 (Large).jpg GMF Drill Sharpener Feed Adjuster 003 (Large).JPG GMF Drill Sharpener Feed Adjuster 007 (Large).jpg GMF Drill Sharpener Feed Adjuster 013 (Large).jpg GMF Drill Sharpener Feed Adjuster 014 (Large).JPG

I had a look at some old photos showing the sheetmetal pedestal GMF supplied and the top mounting plate is offset and drilled to accommodate the attachment of the drill sharpener. It wouldn't fit on a bench mounted grinder unless the grinder was corner mounted.

001 (Large).JPG 005 (Large).JPG 016 (Large).JPG

Thanks for the photos bob.

I had a bit of a ply with the sharpener attachment today but I gave up because it seems to turn through the wrong arc.
It seems to want to remove more metal from the bit at the cutting edge and less metal as the bit rotates so that the cutting edge os lower than the rest of the ground surface?

Anyway I'm having probs with the VFD so I need to sort that out first.