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recommendation for Wire EDM shop, very small random jobs, quick turn around.

dsergison

Diamond
Joined
Oct 23, 2003
Location
East Peoria, IL, USA
I'm looking to find a shop to take over my prototype EDM work.
I own a robofil 290 but it's nearing end of life with no oem support and I do not need another.
I only do about a dozen hours of cut per year with it. Strictly 2 axis cuts under 40mm thick.
I would like someone who can use finer wires like .1mm

What I can't handle is the several week turnaround times of the shops near me. -and the no-quotes because the jobs are too small to bother with etc...
 
I'm looking to find a shop to take over my prototype EDM work.
I own a robofil 290 but it's nearing end of life with no oem support and I do not need another.
I only do about a dozen hours of cut per year with it. Strictly 2 axis cuts under 40mm thick.
I would like someone who can use finer wires like .1mm

What I can't handle is the several week turnaround times of the shops near me. -and the no-quotes because the jobs are too small to bother with etc...

Do you really need .1mm (.004") wire for some reason? I think that could be some of the reasons for no quotes, or maybe quotes that are sky high. We run .01 & .008 wire (sorry we make our own product so not trying to quote or anything) and there is a difference in how fast they cut, not a ton, but I imagine at .004" it would be painstakingly slow = higher cost.


Just a thought...
 
I do two types of work. .010" .25mm wire single pass cuts for almost everything.... except that there have been some tiny detail experiments.

the tiny cuts are a couple square millimeters of total removal so cut time is not an issue. This was experimental work, not to any inspection tolerance. I just want that type of capability possible.
 
I have a small job for a small EDM shop. Either Wire or Sinker should work.

I need to remove a small amount of material in the bore holes of a few Multifix tool holders in order for them to fit properly to the toolpost (the fit is too tight). The bores are about 6mm diameter and the holders are hardened steel.

This would be a matter of removing a few thousandths at most, while maintaining the shape. I believe an electrode made to the same diameter as the posts on the toolpost would work well.

You can see the bores near the bottom the drawing on either side of the toolholder's grooved arc.

Multifix EH Holder Create.jpg

Ideally I'd like to work with a shop within reasonable driving distance from Portland, ME so that I can bring the holder and the toolpost to check fit.

But I would be willing to ship the items as long as the down time would not be too great.

Once the way to do this and the amount to be removed is determined I would like for the shop to keep the electrode and I can order some more holders to be modified.

BTW, all the parts seen on the top of the holders can be removed leaving just the holder itself, which should simplify work holding.

If anyone is interested in doing the work, please contact me via PM or find my email on my website:

CinemaTechnic - Optics for Motion Pictures and Digital Cinema

I may also have other small EDM jobs in the future.

Thanks
 
Hi cinematechnic:
This job is ideally a wire EDM job, and it is going to be all about fixturing the toolholders repeatably and accurately against a plug so they can be cut in correct alignment to the Multifix toolpost you have bolted to your lathe's compound slide.

In my opinion, that's the whole job, and to do that successfully, it will need one of two possible alternatives:
1) You send the toolpost to the wire shop so they can bolt it to a plate and align to it so they can clamp your toolholders against it and wire cut them one after another.

2) the second (and better) way is for the wire shop to wire cut a purpose built plug they can use in the same capacity.

Someone is going to have to model that plug accurately, so it can be used this way, and so it can be conveniently clamped to the machine table.

None of it is difficult, but the cost will not be trivial.

As an economical alternative, have you considered going in with a die grinder and relieving the bits that are too tight with nothing more than a good eye and a steady hand helped along with a bit of Prussian Blue to tell you where to give it a kiss?
Are we talking about an amount you could just lap out with a cheap barrel lap and some coarse Clover compound from the Automotive store?

With a bit of effort and care you'll likely save yourself a thousand bucks easily.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
Hi cinematechnic:
This job is ideally a wire EDM job, and it is going to be all about fixturing the toolholders repeatably and accurately against a plug so they can be cut in correct alignment to the Multifix toolpost you have bolted to your lathe's compound slide...

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Marcus,

What do you mean by a "plug". The toolholders are rectangular. All sides should be square and parallel other than the grooved arc. I can check them to confirm that.

Also a ground part could be clamped into the toolholder to simulate the cutting tool. The tool slot in the toolholder is ground.

It WOULD be possible to use the toolpost because you can remove the grooved center cylinder from the rest of the toolpost. Still seems like a labor intensive setup vs. clamping the toolpost on it outer sides.

I wouldn't dare hand grind... the holes are too deep and I've always found that you can't hand hold a rotary tool in a hole because it wants to touch the inside of the hole and spin itself around.

I HAVE thought about making a rod and using lapping compound. It seems that I'd probably have to make a rig that would spin the rods slowly using a small motor driving with a belt. Seems like a LOT of setup work for a one-time job.

Also I've seen contradictory info on lapping. In some places they say you have to use a lap made of a softer metal and then it will lap the harder metal part. It seems to me that unhardened steel would be soft enough. Brass could be another option.

But is that advice about the softer metal lapping the harder metal true? And if so, it that only the case with "embedding" lapping compounds? I suppose only Silicon Carbide or Diamond would work against hardened steel.

-Jorge
 
Marcus,

What do you mean by a "plug". The toolholders are rectangular. All sides should be square and parallel other than the grooved arc. I can check them to confirm that.

Also a ground part could be clamped into the toolholder to simulate the cutting tool. The tool slot in the toolholder is ground.

It WOULD be possible to use the toolpost because you can remove the grooved center cylinder from the rest of the toolpost. Still seems like a labor intensive setup vs. clamping the toolpost on it outer sides.

I wouldn't dare hand grind... the holes are too deep and I've always found that you can't hand hold a rotary tool in a hole because it wants to touch the inside of the hole and spin itself around.

I HAVE thought about making a rod and using lapping compound. It seems that I'd probably have to make a rig that would spin the rods slowly using a small motor driving with a belt. Seems like a LOT of setup work for a one-time job.

Also I've seen contradictory info on lapping. In some places they say you have to use a lap made of a softer metal and then it will lap the harder metal part. It seems to me that unhardened steel would be soft enough. Brass could be another option.

But is that advice about the softer metal lapping the harder metal true? And if so, it that only the case with "embedding" lapping compounds? I suppose only Silicon Carbide or Diamond would work against hardened steel.

-Jorge

You are overthinking this IMO. You need one of these (search barrel lap on MSC) https://www.mscdirect.com/product/details/05060066 and some clover lapping compound. https://www.mscdirect.com/product/details/00271809 They make different grits, just be sure to clean the lap thoroughly between grits if you are trying to get a certain finish. Usually a coarse grit works fine for opening up a hole. IF you are indeed only talking a few thou. A drill press on the lowest speed (150-250 rpm) will be fine. A couple other things -

1) they make blind laps with a recessed adjustment screw if it is a blind hole
2) You can make your own by finding a slightly undersize piece of rod and milling/sawing a slot in it and wrapping with emery paper, great for odd sizes, but I would buy the one I needed, with lapping compound to do it "right"...
 
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Hi cinema and Mike:
I have a Multifix B toolpost on my Monarch and I also have a wire EDM machine, so I know the potential problems of skimming the clamping bores of Multifix toolholders in a wire EDM very well.
Although the tool holders are milled "square" they're not very square especially since they've been just milled and then case hardened.
The reference surface that clamps to the serrated toolpost was then form ground in a fixture that established the relationship between the clamping bores and the female serrations on the toolholders.
Since case hardened steel swells in hardening, the milled surfaces are no longer flat; they're pillow shaped and will rock if you put them on a surface plate (at least mine do, and they are the original made in Switzerland toolholders).
Some of them have also been stamped with serial and model numbers, so there are raised areas around the stamping marks.
All this means they are not suitable as clamping surfaces in a precision EDM vise, and you no longer know where they are relative to the principal accurately ground feature of the toolholder, which is the concave serrated surface that mates with the serrations on the toolpost.

BTW those locking bores already have a TON of clearance...mine measure 0.354" diameter and the posts they engage measure 0.310" so it puzzles me that yours are too tight.

Back to the subject at hand...if you want to skim those bores in a known relationship to the ground serrations, you need the post or a facsimile of the post as an orientation jig since you can't rely on the outsides of the toolholders and you'll fuck around forever trying to get the holes aligned good enough to wire cut them if you don't.

Mike, your point is well taken, and I fully agree that wire is an awfully sophisticated way to tackle this relatively crude task.

Going back to your problem cinema; it strikes me there is something wrong with your clamping mechanism if you are indeed experiencing difficulties dropping a tool holder over the clamping mechanism and against the toolpost.
Have you taken it apart to see if an arm is bent or a chip is stuck somewhere?
With 0.022" per side of clearance you should not be having the problem you're describing.

Are you SURE both the toolpost and the holders are genuine Multifix and belong together?
Were you aware of the presence of competitors brands?
A German company called Drehblitz made a very similar model and there are countless Asian copies out there of unknown and suspect quality.
I would expect a problem of this sort to be caused by something other than poor quality control from the Multifix factory...my stuff is excellent but it is also 40 years old and made in Switzerland; way before there was a counterfeit market out of China and Pakistan..

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
Hi cinema and Mike:
I have a Multifix B toolpost on my Monarch and I also have a wire EDM machine...
Are you SURE both the toolpost and the holders are genuine Multifix and belong together?
Were you aware of the presence of competitors brands?
A German company called Drehblitz made a very similar model and there are countless Asian copies out there of unknown and suspect quality.
I would expect a problem of this sort to be caused by something other than poor quality control from the Multifix factory...my stuff is excellent but it is also 40 years old and made in Switzerland; way before there was a counterfeit market out of China and Pakistan..

Cheers

Marcus

I thought I had stated it clearly before but I'll sum it up here:

Multifix "A": "Original Multifix" J.F. Minder Geneva toolpost
"Swiss Made" or "Made in Switzerland" stamped toolholders - Perfect fit
Create Tool (China) toolholders - too tight to mount at all (these are the ones I need to modify)

Multifix "E": "Original Multifix Suisse" Mivesa Geneva toolpost
"Made in Switzerland" EFI toolholder - Perfect fit
SPI boxed "Original Multi Suisse" toolholders - tight fit but can be slid on with some wiggling, the cam must be in the loosest position - I don't need to modify these but it's an example of the same problem to a lesser degree

I don't know where the SPI boxed E toolholders were made (not marked anywhere), but it's likely to be Germany. It is deceptive how they were marketed to convince you that they were Swiss. Fortunately I bought them at a good price a long time ago on eBay as New Old Stock.

It seems I should consider honing the holes. The problem is that I don't need to make the entire hole bigger, I need to remove material on one side of the hole only.
 
Hi cinematechnic:
OK that explains the source of your difficulty much better.
I looked at your post #5, thinking I might have missed something important, but could find no reference to the fact you're hoping to mate import toolholders to a Swiss toolpost.
I looked also at your post #7 and similarly could find no reference to what you were trying to mate.
So that's why, based on this "I need to remove a small amount of material in the bore holes of a few Multifix tool holders in order for them to fit properly to the toolpost (the fit is too tight).". from you in post #5, I presumed all components were Multifix and was perplexed at how this could be, given the quality of my own toolpost and holders.

OK, so you will need to take out more than what you can probably achieve by lapping, and since that's the case, it's probably worthwhile to do what it takes to wire cut them rather than sinker them.(sinkering will be costlier)
Here are your choices as I see them:
1) temporarily sacrifice the toolposts to the wire shop so they can use them for fixturing.
2) Use them yourself if you have a surface grinder and can grind some properly flat and square clamping surfaces that are consistent from holder to holder.

However you do it, you must have the means of hanging the holders into the work tank so the upper and lower heads can both travel over the entire top and bottom surfaces.
Bolting the toolpost to a plate and hanging it into the worktank accomplishes that most cheaply.
Then you can C-clamp the holders against the toolpost, leaving the clamping bores accessible.
You can pick up the bore locations of an original Multifix tool holder (if you have one), and can then just wire cut each of the new tool holders to match, by clamping them in turn to the toolpost and running the program.
I estimate the farting about for setup to consume a couple of hours, the programming to consume half an hour and each tool holder to consume about half an hour for both holes assuming you can live with single pass precision and finish (gets you to within 0.002" and 64 microinch finish).
Typical charge out rate for wire shops in my area (western Canada) is $120.00 CDN per hour, so the mod will be roughly 60 bucks a holder plus the setup and programming amortization, if your area has a similar shop rate for wire work.

Making a "plug" simply allows you to avoid stripping the toolposts off the lathes and surrendering them for a few days, but now the plug has to be modeled, programmed and wirecut so it can serve as a surrogate for the tool posts.
It only needs one serration on it, but it still has to be chopped from a big enough plate to hang from the side of the worktank, and the wire is charged out by the distance it travels, not the complexity of the contour it follows, so many serrations costs what one serration costs but one's enough to index from and it's simpler to model accurately.
So if the toolpost is 2" thick, and 3" diameter, the wire needs to travel roughly half the circumference so 5" at 0.100" per minute so call it an hour ($120.00) to wire cut the holding fixture, plus what it takes to model it, program it, mill on a clamping step and bolt holes to mount it on the table, mount it and prep it for cutting.
So you can see where this is going cost wise, and if you have 10 holders to process, you're going to be approaching the thousand bucks I referenced earlier.

Now you have to decide how badly you want to keep the toolposts at home, and how much this project is worth to you.
Be aware also, that the tool holders and the tool posts will likely suffer some surface rusting...it will be minimal if the steel they're made from contains any reasonable amount of Chromium, but there WILL be some.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
Two other thoughts:

Would this not be appropriate for a jig bore?

Or a diamond burr in a mill (MSC Industrial Supply Co.Part #:64140213)?

Not a diamond burr, but a CBN grinding pin. If cinematechnic has a CNC mill, I'd be tempted to find a CBN pin just a little smaller than the bore (which will still be bigger than the clamp features on the tool post), then use just the serrated section of the tool post as the locating fixture and proceed to plunge grind the relocation of the holes.

Start at the holder hole CL, then arc over a bit (~.0005") at a time until you've moved the bore sufficiently. A little tedious to set up, but with coolant flow and patience this can be done on a regular CNC mill. You'd need to play with S/F to get a stable grind.
 








 
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