Chamfering/de-burring holes and grinding folders

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    • Chamfering/de-burring holes and grinding folders

      Happy NY folks, let's hope its better than 2016.

      Just wondered whether anyone has a recommendation for chamfering/deburring small holes in steel/ti? Got some messy 2mm holes to clean up.

      Also, just been practising flat grinds all over xmas (waiting for the large wheel etc to start hollow grinding) and have gradually stopped shaping out a full profile (i.e. incl. handle) for each blade and have instead cut a blank just behind where the pivot would be and use the (approx location) pivot hole to fasten on to the jig. Obviously with a full knife and handle/tang you're good for fixing to a jig but for a folder blade, what are people doing, just fixing by the pivot hole (not great for an eventual precision fit I'd have thought) or leaving an extra section behind to later remove when the grind is complete?

      Cheers

      Marcus
    • I use an "out the front" jig.

      The blade is secured by the pivot hole between two angles mounted on a plate. There is an adjustable support under the blade which stops the blade from rotating around the pivot hole and can be used to adjust the angle of the blades. You can completely grind both sides of the blade without removing it from the jig which helps keep things even and helps prevent warping. It also saves on belt changes and faff.

      This jig only works if you set your work table to your grind angle, also it will take you a few hours to make.

      If you are interested, let me know and I will post some pictures but will not have time till sometime tomorrow evening.

      45 degree carbide burrs are useful if you need to chamfer a hole in hardened steel.
    • @mason knives - used those methods before too, just saw something online about a single flute bit that someone as using very effectively. I suppose that provided the piece hasn't moved in the vice and you can measure the depth of countersink/larger bit descent this would be a way of producing precise, repeatable work.

      I know what you mean about jig versus hands. I started freestyling before xmas but found that one side was producing much better results than the other, so switched to a jig until I get better. Speaking of which...

      @pieinthesky - I'd be interested to hear more about your jig setup and would really appreciate some photos/guidance. I've been using a 7kmetalworks jig and whilst its very nice, you do have to swap sides and that is a lot of faff and downtime.

      Also, I think I'll get hold of a 45 degree carbide burr because thinking about it there's not much point fiddling with this stuff until the end of the job when I haven't funked up the more complex stuff. As above, reckon it'll work well in the mill/drill machine.

      Thanks both!
    • Rode 85k this morning and have ground one blade so I now need to sit down! Pics and a few notes below: (click images to see full size)

      This is the unit complete with a blade fitted:

      Opened up to change the blade: The pivot pin size is not important, use the smallest you are likely to use + washers, then everything will fit. The bar under the blade slides forward/backwards to adjust the angle of the blade and to stop it from rotating..
      You can check your blade tip is central by flipping the blade over and checking against lines scribed on spacer. The spacer must be the same thickness as your blade + washers. (blade looks wonky because of camera angle)

      The two angles + blade can be slid forward and backward on the base plate, you can see the slots in this photo Since the base plate will come up against the edge of the platen, adjusting the blade forward or backward on these slots will determine how far up the blade you can grind.
      I tend to set this so the edge of the platen is a couple of mm from the final plunge line position. This means you can leave the plunge untouched until you are on the finer belts, then hang the edge of the belt over the platen and gently grind the plunge.

      Hope this helps and let me know if there is anything I haven't explained well.

      Edit You can also use this jig for fixed blades - just remove the pivot and the blade support bar, drop the blade between the angles and clamp it together with a small g-clamp. Alternatively drill some holes through jig to line up with holes in blade tang and fit some bolts.
    • @pieinthesky 85k - good effort, no thanks! Seriously though, appreciate the photos and description. I think that I might be able to rig up something similar using the 7k jig I already have by getting a heat sink and sandwiching the blade between it and the face plate, then adding the angled section of bar and a spacer. The jig and heatsink come with threaded holes, which should make it fairly straightforward. Having said that, I'd still have the faff each time I wanted to switch the grind to the other side. I'll test it out, otherwise I might make something similar to yours. When did you source the angled alu?

      Actually, I've just been down to take a look at the grinder/jig setup and I think that what I've got already performs the same function in terms of adjustability, although it does need to be swapped over each time and I can't quite get the same grind on both sides, which I was putting down to technique, unless you think it might be jig related?

      The post was edited 1 time, last by monkeyboy_marcus ().

    • monkeyboy_marcus wrote:

      @pieinthesky 85k - good effort, no thanks! Seriously though, appreciate the photos and description. I think that I might be able to rig up something similar using the 7k jig I already have by getting a heat sink and sandwiching the blade between it and the face plate, then adding the angled section of bar and a spacer. The jig and heatsink come with threaded holes, which should make it fairly straightforward. Having said that, I'd still have the faff each time I wanted to switch the grind to the other side. I'll test it out, otherwise I might make something similar to yours. When did you source the angled alu?

      Actually, I've just been down to take a look at the grinder/jig setup and I think that what I've got already performs the same function in terms of adjustability, although it does need to be swapped over each time and I can't quite get the same grind on both sides, which I was putting down to technique, unless you think it might be jig related?



      Use two bolts!


      Have one so it's barely projecting so the spine presses down on to it. The blade doesn't have to project out the side and will get a better heat sink and support from the jig if moved over.
    • @flipmeb and @Stew - you're both correct, the photo was just for illustration. I grabbed a blade I was working on a couple of nights ago and bolted it on. Previously I've not had the blade at such an angle and have had another bolt below. However, I've had the blade hanging out over the side all the time, so maybe I should bring it back over the faceplate more?

      @pieinthesky - couple of photos of either side of this blade. Difference has been getting less pronounced and I've been coming at the belt from a piece of 30mm steel bar that I've clamped to the platten, which is hardly ideal and that has been because I've had the blade extending off the end as illustrated. I've another slab of alu coming tmw to make a bigger work table and will experiment tonight with having the blade more centrally positioned on the faceplate, see what happens!

      Going right to left I tend to get a nice straight grind line, whilst left to right tends to be more curved. Hopefully the work table and repositioning of the blade will help. Off to make some noise now...

    • Interesting hour spent in the 'shop. Got the blade more central, still had the tip poking over so as not to graze the jig and considering this was the first attempt at this method, with a downward blade and new shape, the results weren't too displeasing:



      Obviously blew the grind line going left to right with no room to correct, which is the weaker side and did the tip freehand as an afterthought but considering that I'm expecting to junk many metres of mild steel before I even get semi serious about producing anything worthwhile, I'm not complaining.

      Thanks for the tops and advice fellas.
    • Looks like you just need practice to me. It is very easy to go wrong with sharp/coarse belts and soft steel. If you can get it right on mild steel you will find it much easier on hardened steel - but slower of course.

      You are effectively grinding one side right handed and one left handed, your body works slightly differently each way and you need to overcome this.

      It sounds obvious, but try and do exactly the same each side. Bring the blade up to the belt in the same place, at the same angle, move it the same distance at the same speed with the same pressure etc etc.

      When I grind I very gently bring the tip of the blade to the middle of the belt (at a shallow angle) and feed the blade in gently until it feels straight and then grind up to the plunge and back to the tip keeping the blade perfectly parallel to the belt. I find you get a lot more feel for what you are doing this way compared to starting at the plunge. You have to be gentle with the tip though.

      It might be worth getting some dychem and marking your grind lines (see my first pic) I used to mark 3 or 4 grind lines at various heights and would grind to the first (on both sides) then the second etc. This helps keep things even and gives you several practices at getting things straight before you get to the one that matters. (Marking grind lines accurately and correctly takes a bit of thought - but that is another subject altogether)

      Google and read around and try all the different suggestions you can find and see what works.

      If you are making a bigger grinding table it can be useful if you make a cut out in it so is wraps around the platen. It gives more support for your jig and is essential if you use an out the front type like my pics.