Making Our Own Bullet Guides

Hello everyone! First post for me. I figured I better get on here and start utilizing the vast knowledge PM has to offer.

Ok, so we have a Current EDM CT400 Drill that we use for deep hole drilling of sized holes ranging from .030" to .200" using brass electrodes mainly thru stainless. The electrode guides or bullet guides, as our supplier calls them, are costing us around $150 a piece for a standard guide??? When we purchased the machine a year ago we needed to hit the ground running and bought the sizes we needed but now that some are wearing out I want to start making our own.

1. Are any of you guys making these guides?

2. What material are you using or what should I use? We have some 17-4 or 455 stainless on hand but not sure if I should make them out of some pre-hard and them send them to heat.

3. what kind of fit works best for the electrodes. Some of the guides we have received are over .002 clearance which doesn't really make sense to me. What would be the tightest fit without risking locking it up the guide when running. we have to hold position pretty tight.

4. What about possible coatings? like A TiN or even hard coat chrome.

My plan would be blank out a bunch of these on the swiss and hole pop them with the smallest size we have and then use the wire to bring them to whatever size needed.

Any insight would be Great.

Thanks!

Tom

You are going to use SS for the guide body, that's good ... but what are you going to use for the actual guide?

I don't know about your guides but ours have synthetic ruby inserts that do the actual guiding ... and keep the electrode from grounding out through the guide instead of burning a hole.

Are your guides all SS and isolated from ground or do they have an insert too?

If they have an insert, how are you going to secure it to the guide body and more importantly ... how are you going to size it?

Our guides are an unknown to me steel/SS and yes they are isolated from ground so it is a metal on metal situation. The whole guide assembly is mounted to the head by a plastic block/spacer.

Darn, and here I was all ready to learn some new gunsmithing trick. I figured it was a loading thing, or maybe a euphemisim for iron sights that I hadn't heard before.

We have some here that were wired out whole...that is, outside plus a slot to the inside and the inside (no hole popping required.) They seem to have a couple of tenths clearance. They work fine down to .030 with the slot, and they position just fine to less than a thou. Don't know what they were made of, maybe 420?

Isolated head or not, having Plane Jane steel guides is just dumb.
Shame on Current for even doing so and STILL charging more for the guides than the ceramic inserted ones used by most others.

The fact that you're wearing them out proves the ill design of plain SST guides.

My recommendation: Either buy or make an adapter for your machine, ditch the Current guides and go with the standard ones.
Virtually all EDM suppliers have them for various prices, prolly around the same as what you're paying ( perhaps even less )
and you will not wear them out so quickly.
I think Global EDM actually has the adapters.

As far as the tolerance, I wouldn't go too tight on the fit.
Yes, the electrodes SHOULD be on size and round within .001-ish, but you will still be binding up due to the fact that the drilling debris will coat the electrode.

SeymourDumore said:

Isolated head or not, having Plane Jane steel guides is just dumb.
Shame on Current for even doing so and STILL charging more for the guides than the ceramic inserted ones used by most others.

Click to expand...

Exactly! I am not to impressed IMO with Currents entire setup but that is for another discussion.

They do have sapphire guides but at least double the cost with huge lead times. I just reached out to Global EDM as you mentioned for the adapter kit and they are working it out on their end. We are capable of fabbing something up in-house to make it work so I am more and more now thinking to completely change the entire guide setup. Whether that be in-house or off the shelf only time will tell.

Thanks Sybilsurf for sharing your method! I have thought about something on those lines just wasn't sure if it would have been perceived as crazy or makeshift so good to know!

Are you asking current for a specific size?They sell the blanks for about $40.00 ea.

Right the blanks are available but I am hoping to make something last a little longer. At $40 bucks a pop for a blank id like to believe we could make something similar and stock up on a lot of them for a lot less. What cost do some of the other brands/setups run?

EDM Tech Center has Current parts, Current OEM Guides, economy replacement guides, guide adapters, and can custom make any guide you may want.
763-315-9104
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