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Thread: Your latest project
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26th Dec 2016, 09:17 PM #1741Golden Member
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Hi Dean,
The modification you are doing is similar to the changes I made to mine around four years ago. Good idea to fit a new blade, you should be able to then get a nice square cut in both directions. One other thing I did was to clean up the top of the round section on the top of both castings and when you are happy with your set up you can scribe a good clear mark across both pieces, makes it easy to see if they have moved in the future and quick to realign.
Bob
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26th Dec 2016, 09:22 PM #1742
Thanks Bob. That sounds like a great idea. I will do that.
Dean
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26th Dec 2016, 09:22 PM #1743Most Valued Member
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26th Dec 2016, 10:40 PM #1744
I rarely handsharpen these days (out of practice) and I had to go out and grab a drill bit to double check. I do hand sharpen the same way, but the edge is pointing down so the wheel surface crosses the drill face in the same direction as my jig works.
I realised that I should actually point out the mods as it is not easy to see a couple. One is not visible.
If the picture is looked at full size it will be seen that the pivot occurs on an added cylinder with a shoulder. The jig shaft is mounted in this cylinder, in a hole that is offset from centre. A grub screw locks the shaft in position. This is to allow adjustment of the offset between the pivot and the drill bit centre.
The unseen mod is between the HDPE base and the sliding ways. I does not look like it, but there is an ali block around 25mm high between the 2. This block is miiled on a taper so the jig leans away from the sanding disk about 6 deg. This is to counteract the incorrect angle provided by the jig. Without the taper the bit will be sharpened at about 130 deg. This is apparently common to just about all of these jigs. The angle can vary from different manufacturers.
The most obvious mod is the sliding ways. These are just to make it easier to position the bit with regard to the sander disk surface. The black knob locks the ways. In front of it is a screw that locks the jig to the sliding part. The jig base had to have quite a bit of the face milled off to avoid it hitting the sanding disk.
I added a locking ring for the adjustment, on that 1/4" thread at the right. It was useless without this. There was only 2 rings before. I use the outer 2 as a stop to set the max travel to just clean up the worst looking flute, a bit at a time. The bit is then rotated to the other flute and ground a bit at a time until coming up against the stop again.
The jig still needs a better clamp to hold the bit in place. With larger bits the flutes don't always suit the vee and clamp and the bit sometimes won't sit flat.
Except for the sliding ways, this information is from a guy called Graham Meek. I printed some of this information a few years ago. I have not been able to find all this info again. I have found some of it here Drill grinding jig 1
and the next page. I am glad I still have those printed pages. I see he has added some more to the design. All of page 2 stuff seems to have been modified or added since I read it last.
Dean
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27th Dec 2016, 09:44 AM #1745Most Valued Member
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27th Dec 2016, 11:30 AM #1746Golden Member
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27th Dec 2016, 12:21 PM #1747
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27th Dec 2016, 01:25 PM #1748Pink 10EE owner
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27th Dec 2016, 10:09 PM #1749
Dean,
The instructions for my toolgrinder mention this. They prefer grinding towards the cutting edge because that prevents the formation of a bur.
Ik think the only reason they give for grinding the other way is because it pushes the tool you are grinding against the support finger (I don't think that applies here), but then you would need tot debur the cutting edge.
I hope this helps,
Peter
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28th Dec 2016, 10:53 AM #1750Most Valued Member
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28th Dec 2016, 12:11 PM #1751Senior Member
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I'll admit I didn't approach it with as much of a plan as I probably should have... had recently bought a hex collet block so mounted it in that and had at it with the mill.
Angled the collet block up a little in the vice to get it close to being flat across the top but with the nose tipped down a little so it would cut deeper at the back, tilted the mill head 15 degree and lined up the cut entry point at the end on about centre line and had at it. The rest was really just trying to cut reliefs. Don't have stones to really clean up the cutting edges but used some files and a 240 grit belt on the linisher. I tried for a 3 flute cutter thinking it would help keep it centered in the material.
This is where I am up to with it so far, it sorta cuts but not real happy with it, the small end cuts better then the big end, not sure if it's just because it's cutting a bigger diameter open or if the angles ect change. Open to suggestions on what I have down wrong/ how to make it work better, this is my first attempt and was more of a "I wonder if this will work" kind of thing.
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28th Dec 2016, 12:29 PM #1752
On further investigation I found that the grinder shaft and nut prevents the jig from being used on a normal grinding wheel. I wish I did not have to cut the grinder guard to work this out. I would need to get a cup or bowl type wheel to do this, but I think the cost will be prohibitive. I have not been able to find one which would suit. It would be easier to have a 200mm wheel and the contact surface needs to be wide enough to suit the largest drill bit. Any other size would mean a redesign of the jig mounting system to enable height adjustment.
The issue with the sanding disk is that it is velcro mounted which means that it is difficult to tell when to stop grinding so both edges match. I might try positioning the jig just in front of the shaft/nut and see what happens
Dean
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28th Dec 2016, 08:11 PM #1753Most Valued Member
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I could be barking up the wrong tree, but the way I see the problem, is that there isn't enough relief at the top of the taper. Looking at IMG 2568, at the bottom you have what appears to be a couple of mm but at the top there is something like 10 mm of material rubbing on each segment. What needs to happen is to grind a mm or less away, like lands on a drill bit, to give access for the cutting lip.
Hope I explained it well enough.
KrynTo grow old is mandatory, growing up is optional.
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28th Dec 2016, 08:30 PM #1754Pink 10EE owner
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3rd Jan 2017, 02:18 PM #1755Philomath in training
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I've been trying to think of a good way to remove grinding wheels with hubs on and with a bit of experimentation, think I've found a way. (The alternative is to fish around with a pry lever behind the wheel and I'm always concerned that I'll lever on the grinding wheel instead of the hub).
It's made of 3 main parts plus a roll pin to keep everything together. The part with the knurl is a stepped nut with 2 LH threads in it, one 3/4" 20tpi and the other 1 1/4" 20 tpi - the larger to match the thread on the hub. The part to the right is essentially a hollow bolt, again with 3/4" 20tpi (LH) thread. The flanged spindle does the actual pushing.
P1030789.JPG
It assembles like this, with a smear of grease on the back of the spindle flange so that the bolt can push against it. The bolt thread is LH to match the spindle so one does not unscrew while the other is screwing up and everything is 20tpi because that is what the hub threads are and I was too lazy to change. The ropey looking knurl is a last minute addition as I noticed when I tried it that the bright material was a bit slippery. Apart from the roll pin, all from the scrap box.
P1030790.JPG
And this is it in use. I did consider a hex nut but as the hub nut used a pin spanner I went for convenience. To use it the knurled nut is threaded onto the protruding hub thread and then the 'bolt' is screwed in. It pushes against the flanged pin that is in contact with the end of the spindle. Being a taper once the seat is disturbed it just pops off, so this just to break the seat without stressing the wheel. I have a number of hubs so I can swap mounted wheels with just a quick dress I hope.
P1030792.JPG
Michael
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