Hi guys,
I am struggling to drill an EVA grip handle. I have no Idea how to do that best. if I am using a regular drill bit the I am ending up with a mess of an unusable handle.
Anybody can give me a hint?

Bruno,
The best thing - when enlarging most rod handles - is to ream them, not drill them.
The reason is that most handle materials - like EVA - are relatively soft and can either tear or chunk out - when hit with a sharp drill bit.

But, if you use a sand paper coated reamer, or a circular file - spun backward, will simply enlarge the hole without doing any tearing.

Good luck
Roger

p.s.
The best thing to do with EVA however, is to purchase the right size grip with an internal hole that is already sized to fit the blank. That way, coat the rod with epoxy, coat the inside of the eva and simply slide the grip in place. A typical EVA grip can stretch about 30% if you do it in one smooth motion, wiht both the rod blank and the inside of the EVA well coated with epoxy.

Roger

more of a ? than a reply. would the reverse pilot bits work on eva?

Ricky,
Really the same issue with the reverse pilot bits. As soon as this cutting edge hits the end of the eva, it is going to start tearing chunks of EVA from the grip.


You could certainly give it a try, but my guess is that it will not be satisfactory.

p.s.
The one thing that might work with the reverse pilot bits, is that after putting the bits through the grip, and getting them into your HIGH speed drill is to advance your drill to its maximum speed, before getting the bit near the end of the eva.
It will take a steady hand and a good bit of nerve to do this, but the very high speed of the drill bit, might better simulate a sharp cutting tool to shave off the EVA.
I don't mean that you should use a cordless drill that only turns up to a 1000 rpm or so. but prefererable a drill that would spin up to at least 2500 rpm.

Be safe and don't hurt yourself.

Roger



Edited 1 time(s). Last edit at 04/04/2011 07:45PM by roger wilson.

thanks roger, the reason i ask is the last rod i built had a .618 butt and split grip was .450 hard eva. i did ream it some and worked fine. you are right running the bit like you say would be dangerous especialy on a small fighting butt. thanks ricky

I ream EVA handles on a daily basis. Several things you can do - you can impact the firmness sometimes by reaming more or less, you can also reduce weight by reaming also.

I usually ream mine to the same place I would cork - maybe a 1/4" higher just so when I slide it down it has a nice snug fit and there are no gaps on the internal bore on either end.

EVA reams so easily, I personally don't see the point in fighting one down by stretching it out.

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this was my first large blank with eva. the one thing that did happened was that when the rear grip was in place the teton for the reelseat did expaned some and had to be turner down a little. maybe should have reamed it a little more. this was a different game than the light and ultra lite rods i have been using eva grips on. (always something to learn) ricky

Got that, I ream the grips as well IF there is allready a smaller diameter bore. But what I am trying to do is to start from a block material, without any bore, put it on a mandrel and turn it on the lathe.
One possibility I see is to cut the EVA in slices, and stamp the initial bore then adhere the slices together, but I would like to avoid this cutting thing.

Bruno,
If you are starting with just a block of EVA - you can use a rotary rasp to cut through the material.
You can also use a standard drill bit - running backward. By running the drill bit backward, it won't cut like it would if you had it running forward.

The 3rd, and possibly the easiest thing to do is to start with a standard drill bit. Put the head of the bit to the grinder and grind the head of the drill flat.
Then, regrind the head of the drill bit with a slightly negative cutting edge, as well as a slightly down turned tip.

i.e. essentially make the correct direction turning drill into a reverse running drill by reversing the slope of the cutting edge of the drill bit.
You can do a bit of experimenting, but if you get the head of the drill bit almost flat, you very much reduce the tearing of the handle material.

If you get a hole of any size through the eva block, you can go to a full length machinest reamer to clean out the hole very nicely. The full length machinest bits, have straight cutting edges running the full length of the drill bit parallel to the length of the bit. Since there are many multiple edges on these machinest reamers, they do an excellent job of cleaning up a hole in eva or cork very well.

Here is an example of a 1/4 inch machinest reamer that leaves a velvet smooth hole in EVA and cork:
[www.grainger.com]

I keep a couple of the reverse topped drill bits by my lathe to work with handle and other soft materials to avoid ripping and tearing.

Then, when it comes to shaping the eva, just use a Stanley Surform planer. The straight rasp that is the surform planer does a quick job of shaping the eva to the rough shape. Then, simply move to various grades of sandpaper for the final shape and finish required for the application.

Take care
Roger

Bruno, what tools do you have available to you? Do oyu have a wood lathe like a JEt or Delta or something? Do you have a drill press?

To bore it out on a lathe is not hard provided you are set up to do it with a jacabos chuck and for mea 4 jaw chuck like a nova. All you need to bore it out are brad point bits or Irwin speedbore bits - you need to get long ones to go all the way through. Boring from both sides isnt' always the eaiest thing to get the hole to mee in the middle.

Turning the EVA from square to round is easy - [www.youtube.com]

Billy,
If you do this job on the lathe, and the fact that you mention a 4 jaw chuck - I assume that you are holding the work piece in the chuck and then holding the drill bit stationary in the tail stock?

Then, do you use a short brad point bit to get the hole started and centered on the work piece before going to a longer through hole bit?

Thanks for any updates.
Roger

Yes. Thta is why I asked what tools he has available to him. There's more to it than that, but you're right that will work for those w/o a 4 jaw chuck. If you want to be precise thisway is not 100% accurate, but it's OK. Dilling the center perfectly without a drill press or lathe is not very easy.

You can use Flex Coats reverse pilot bits on Eva just as you can with cork. As the name implies, reverse, you use it on the reverse setting of your drill and it won't tear any chunks out. Run it through halfway then turn the grip around and pull it through the rest of the way. A lathe with your reamer is the best and most accurate way to ream your grips.

Lance

Lance,
With respect to using the reverse pilot bits with any handle material.
Yes, you can use the reverse pilot bits with any handle material.
I have personally found that if I try to take a 1/4 inch hole and enlarge it to a 1/2 inch hole in one pass, I stand a good chance of ripping or nicking the edge of the hole with the reverse pilot bits.

So, when I choose to use the reverse pilot bits. I take a reamer - even a fairly steep rotary rasp to increase the hole size in the grip that I am wanting to drill - before using the reverse pilot bits.

Then, essentially the hole that is being drilled by the reverse pilot bits - starts about 1/4 inch inside the outside edge of the grip. Now, even if there is a little nick in the handle material as the bit starts to cut, or chunks out a piece of the grip, it is on the inside of the grip where it does not show. The same is true for the opposite end, when I use the reverse bit there. i.e. I start with a reamer or rasp to get the visible hole to the finished size. Then, finish the through hole with the reverse pilot bit.

Take care
Roger

I do have a lathe and drill press available the lathe is a metal lathe though. I have 3 and 4 jaw chucks.

so basically those irwine drill bits are those paddle type bits, right? those which have a cutting edge on the very outer sides. I`ll try those if I can get them in a decent lenth.

Drilling from both sides is always a mess, it is virtually impossible to center the two bores.

it is also very helpful the idea to use those drill bits with a negative cutting angle!

Thank you!