Vevor M13A drill bit sharpener, split point questions

[homebrewed]

I recently got this drill bit sharpener as a birthday present to myself. It seemed to have decent reviews (in contrast to some other Vevor products). It arrived a few days ago and I had an opportunity to try it yesterday and today, and now have some questions regarding its performance and adjustment.

In a video demo by Mr Pete, he indicated that the adjustment knob on the left side should be turned all the way clockwise, then backed off one complete turn past the drill max-diameter of 13mm before setting the dial to your drill size. So far he's the only one who has said this. It also is not what Vevor's owners manual says. Based on my experience so far, his suggestion is incorrect. So my first question is: what's correct, in other owner's experience? This operation sets the orientation of the drill's cutting lips w/regard to the ER20 collet holder so it's a critical step.

My second question is about the split point operation. As a preface, I have been using the 118 degree setting not 135 degrees. And in that vein, some online sources have indicated that the split point operation is best suited for 135 degrees, not 118 degrees. So my next question is: is that correct, in other owner's experience?

My third question also is about the split point function. With the factory settings, it didn't work. It produced a bit with a profile that looked like the drill had been ground too far back. So my final question is about the adjustment for achieving a properly functioning split tip. Have other owners found it necessary to adjust the grind depth? According to the Mr Pete video, one is advised to leave the adjustment alone. I've been using my stereomicroscope to examine the bit so I'm certain what it looks like after it's been ground. I've been sneaking up on a profile that looks like the one in the owner's manual and to do that has required some significant adjustments. Hence my question.

 

[RJSakowski]

Regarding advice from Mr. Pete, I trust but verify. I have found him to make erroneous statements in the past and that is in regard to subjects for which I have knowledge. How can I believe him concerning topics that I have no knowledge?

 

[f350ca]

I recently purchased one as well. Haven't had time to play with the settings but the left hand adjustment seams to be spot on right out of the box. Set the dia and go. Does this change the orientation or the amount of material removed? I suspect the depth of cut.
On a side note was recently drilling out a tie rod end for a hay wagon. Im sure it was pretty soft steel. Made a 3/16th pilot hole then used the Vevor to sharpen a 1/2 in bit. It started self feeding. Never experienced that before in steel.
I think the model I have thins the web rather than make a split point. Tried it once, but didn't examine the results very closely. Have never used split point bits.

Greg

 

[homebrewed]

Regarding advice from Mr. Pete, I trust but verify. I have found him to make erroneous statements in the past and that is in regard to subjects for which I have knowledge. How can I believe him concerning topics that I have no knowledge?

It's a wise man who is comfortable saying "I don't know".

 

[craniac]

Here's a link to a video I thought was good about the vevor. I'm thinking of getting one. It's the second half of the video where he demonstrates the vevor.

 

[homebrewed]

Here's a link to a video I thought was good about the vevor. I'm thinking of getting one. It's the second half of the video where he demonstrates the vevor.

Based on my many failing attempts to create a split point grind on my M13A I had started to suspect that the angle-adjustment operation on my machine isn't working right. The video basically confirmed my suspicions -- the author of the video stated that he aligns the drills by eye because the adjuster wasn't all that accurate. All he uses it for is to set the stick-out of the drill. Maybe Mr Pete's comment was correct.

What I observed is that it was necessary to greatly increase the depth of the split-point grind compared to the factory setting. And even then, the bit was screwed up because the remaining cutting facets were razor-thin at the tip of the drill. It might do a fantastic job of drilling plastic, maybe even aluminum -- but attempting to use it on steel would wreck the drill. The cutting edges would crumble.

The video was useful in another way. The first part about the Drill Dr and pressing the grinding wheel in a bit more to get the right relationship between the drill and grinder showed me what to look for on my M13A. I liked the custom "press" he used .

Thanks for the link!

 

[homebrewed]

I think my suspicions regarding an alignment problem are correct. This is based on some measurements I did, using a length of 1/2" drill rod I faced (I use it for alignment purposes on my mill and lathe).

First, some terminology to make it easier to describe the relevant parts of the grinding machine's alignment fixture. The fixed part is the "base", and the adjustment knob screws into the base. The top of the base will make a handy "reference plane". The moveable top piece is called ..... the "top piece" . Or "adjuster".

Here's a photo of the top piece:



The portion of the top adjuster piece where the ~45 degree angle is extends down below the top of the base. When the adjuster is cranked all the way down, the bottom of the angled part extends 5.24mm below the reference plane. The bottom of this region is flat -- co-planar with the reference plane. I used my caliper to measure that offset so the design target could have been 5.25mm. When drill bit alignment is performed, the adjuster dial is set to indicate the drill diameter in mm and the drill lip on the left side of the drill is rotated until it touches the adjuster -- it's a stop. Then the collet holder is tightened down to hold the drill in place for the grinding steps. In this way both the angular position and stick-out of the drill is set.

Next I installed my 1/2" (12.7mm) drill rod in a 13mm ER20 collet and pushed up against the bottom block, then tightened down the collet. The top of the rod was 1.58mm "proud" of the reference plane. I know that the center of the rod represents the tip of the drill bit, so the tip of a drill bit will be (12.7/2) - 1.58mm = 4.77mm below my reference plane. Then I switched things around a bit.

I removed the adjuster and set my caliper to 4.77mm so its "tail" extended that far. I swapped out the 1/2" rod for a 3/8" drill bit, which is close to 9.5mm, and used the caliper tail as a stop instead of the adjuster. Tightened down the collet nut and examined the drill. Its lip was nicely aligned with the flats on the collet holder, which is what the owner's manual says should happen. Then I re-installed the adjuster and tightened it down until it just touched the drill lip. The above photo was taken with this setting -- and it clearly shows that the adjuster is nowhere NEAR indicating 9.5mm. The "9.5" should be close to the 12 o'clock position, not the 4 o'clock position. Looks like a problem to me!

I think the whole approach for this procedure is suspect. I mean, the adjuster dial indicates vertical displacement according to drill size -- but the drill lip, no matter what size drill it 's on, should be at a constant height relative to the reference plane. Maybe the helix portion of the drill bit causes some problems that require changing the adjuster height, but whatever the reason, it sure doesn't seem to be working correctly on my machine. The angled profile of the stop is there to avoid fouling the body of the drill so it can function as desired, has nothing to do with the drill helix. So......???

At this point my tentative plan is to make a replacement top piece. It will have a slot for the adjuster knob so it can be moved as needed to accommodate the particular drill being sharpened. It will NOT have any vertical adjustment, it will be fixed so the stop's height is always the same. Right where the tip of the drill needs to be. I will make it out of steel to make it less prone to wear. Maybe harden it, that remains to be seen. For initial testing I will use 6061 aluminum.

A totally different approach would be to make a piece that can be adjusted in the horizontal plane. Use the old adjuster screw hole to mount it. The adjustment could be calibrated for drill size so it would be easy to "catch" the lip of the drill. It wouldn't require a very large adjustment range so a fine pitch adjustment screw would be needed. The stop would have a triangular profile similar to the original design.

 

[Supergleep]

I just bought the same drill sharpener after seeing Watch Wes Work's Youtube review as well. I spent a couple evenings playing with some old drill bits and figuring out how to make it work. I also watched Stefan Gotteswinter's review/use of the Motom drill sharpener the Vevor is trying to "emulate". In watching Stefan's explanation of how the Motom works, I realized I was reading the Adjuster wrong. I was looking at the 6:00 o'clock position of the dial for the reading, but it's actually read at the 12:00 o'clock position.

As best I can tell now, when you insert the drill bit you push the tip of the drill into the base that the adjuster block rides on. This sets the stickout length for the drill bit.

The adjuster is then set to the appropriate drill diameter (in mm) and you can twist the drill bit cutting edge to the bottom of the angled part of the adjuster block. This should set the cutting edges of the drill to be parallel to the horizontal ledges of the collet holder. Now you can tighten up the collet and sharpen the drill.

 

[homebrewed]

This should set the cutting edges of the drill to be parallel to the horizontal ledges of the collet holder.

That's not how it is working on my machine. I've been using the 12 o'clock position all along so that's not the issue. My previous post showed a substantial difference between the recommended setting of the knob and what was actually required to properly set the lip. I had thought that perhaps Mr Pete's comment about first backing the knob out one full turn before setting it to the drill diameter was correct, but my result doesn't agree with that, either.

I would be interested in comparing my measurements to other owners' to see if my machine's alignment hardware is defective or not. Maybe the bottom of that triangular part of the adjuster is supposed to be sloped? Maybe it's not the right height? You'd never know unless you took the adjuster off and measured/looked at it.

I haven't tried contacting Vevor's customer service folks yet. Not really expecting much from them anyway.

 

[homebrewed]

I've been doing some characterization work on the M13A's alignment fixture. I found that the coplanarity problem becomes worse & worse as the drill size increases. For a 9mm drill the knob had to be set to about "13", but the "5" setting was pretty close for a 5mm drill. A 3mm drill might require a setting less than "3", I need to check that. The 5mm drill I ground turned out really nice so the rest of the grinder works pretty much as claimed.

Contrary to Mr. Pete's comment, the height-adjustment knob is NOT turned one full turn before setting the dial. Crank it all the way down then turn it CCW to the desired number on the dial.

Examination with a hand lens showed that the adjustment device doesn't touch the outer portion of the lip on larger-diameter drills, the contact point is close to the center axis of the drill. It's possible this is due to an incorrect angle on the "landing pad" portion of the tool. Maybe it's optimized for a different drill profile??? I have a really cheap HF jobber drill set. I think I'll re-grind one of those to 135 degrees and see what happens.

I expect the error to have a linear dependency so it should be possible to calculate what the proper setting, as shown on the adjustment knob, needs to be. I may make a little fixture to improve the repeatability of the settings, right now there's a large gap between the PSA-attached fiducial on the grinder body and the dial. A 3D-printed extender would work. It doesn't matter what the knob setting is, as long as it's consistently set. A linear fit will take care of a fixed offset. Y = mX + b and Bob's yer uncle .