Super-Zero Fixture

[mrdovey]

Every now and then I come up with something to make work on my 'Bot a bit easier, and this week it's a gizmo (with supporting SBP code) that lets me zero all three axes to a workpiece in one shot.

This evening I did a redesign to accommodate a cross-hair attachment which can be placed over any point on the table - and plan to write another software module to report the position of that point.

It's rather like a z-zero plate on steroids.

My questions for other 'Botters are: Would it be useful in your shop? If I offer this as a product, along with the SBP code that makes it useful - would there be enough interest to make it worth producing? What strikes you as a reasonable price?

Feedback - either on or off the forum - will be welcome.

[beacon14]

I'm certainly interested but I'd need more details before I could tell you how much I think it's worth.

[myxpykalix]

Morris,
I guess i might be in the minority but i can't visualize what you are trying to make based on your description. Do you have any more details or a picture? I don't understand how this would work?

[mrdovey]

I'm not sure what details you'd like...

It connects to the line you currently (sorry, pun intended) use for your z-zero plate, measures approximately 2" x 4" x 1/2", and locates either one corner of an axis-aligned workpiece or the center of the crosshair (depending on which SBP module is invoked) within one x-, y-, and z-axis step. As with the normal z-plate, it can be used to zero the z-axis to either table or top of workpiece.

Since I made my previous post I realized that I could add a small 'tweak' to the existing code and either return or set the actual bit diameter to the same precision, and I might be able to determine the number of flutes on the bit.

[mrdovey]

Jack...

Visualize a 2x4x1/2 aluminum block. It has some machined features, but it's basically an electrically conductive rectangular block.

I'm not trying to make one - the original is sitting beside my keyboard right now.

If you had a picture and did understand how it works, I would already know your answer about a reasonable price and I could have saved the effort of asking.

[myxpykalix]

See, i guess i didn't "get it". If you send a picture people won't need to buy it they would copy it? DOH!!

Rather than you describing the design or how it works can you tell me if i understand this part correctly.
If i have your device in place of my Zzero plate when i set it (I assume to the lower left corner of material) it will somehow zero all three axis's? If so that sounds like something i'd be interested in.
For me, i'm not the kind that want's to reinvent the wheel by trying to copy the design and make one myself being afraid i might mess something up. I would rather buy something that i know someone got all the bugs out of.
So the only mitigating factor for my decision abviously is price.
You might start with what is the cost of the Zzero plate we now use. Look at your cost of material, time involved in production and set your profit margin to come up with a price. Maybe do some type of informal survey to see what kind of a market you might have. If you know you only have a market for 5 might make it not worth foling with, on the other hand if you have a market for 500 that would help your decision.
I have an email to you with other ideas that might help you.

[mrdovey]

Jack...

Looks like you got it exactly right - and yes, all three axes.

I did start with the z-zero plate price and figured that at ShopBot's price of $75/axis, a three-axis device would come to $225. Then I thought about a reasonable price for a cross-hair point-at-a-time digitizer and added $150. The total of $375 seemed a bit high. At that point - because perhaps great minds do think alike - I decided that I'd better find out how many people would be interested and what they might be willing to pay.

I decided to go to the forum to do an informal survey. Smile, you're on Candid Survey!


I'll watch my mail box.

Lou...

It works well on my PRT, but I honestly don't know about the PR. If that's what you have, and if you're interested, then it might be a good idea to check with the SB folks - and to find out how to connect to your controller as an input.

[henrik_o]

If this really works, I'm definetly interested.

I'm too much of a novice to properly understand the full utility of this item, but my assumption is that it's not for nested base machining but more towards jig-based point-to-point machining.

As for a price point, I'm not sure. If it really provides a rock solid out-of-the-box working solution that can be utilized in production settings, then you could probably double your target cost and still sell copies. I mean, if this meant I could just slap a jig for p2p machining on the table, make sure it was aligned along one axis, and then attach this item of yours and be all set to run my custom file, that would be worth a lot, I figure.

If, on the other hand, it's more of a nice-thing-to-have-for-one-offs, then most people would probably be a wee bit more price sensitive.

But as I said, I'm still very much a novice so what do I know.

[mrdovey]

It really does work. I only have a PRT96 for testing but, as far as I can see, it should work well on other machines without problem.

As a set-up jig (and after a one-time self-calibration using a supplied SBP file) it can locate any of its four corners within one step - without moving the bit outside the block's "footprint".

When used as a crosshair digitizer it registers the crosshair center position with an accuracy of plus/minus one step - probably more exact than the hand/eye coordination of the person setting it in place.

If your cutting is limited to cutting parts from a sheet (with a scrap margin around the sheet edges), then the fixture won't be any more useful than a normal zzero plate.

There hasn't really been much feedback, but I'm planning to offer the fixture and associated software until the end of the month at an introductory price of US$200, and after the introductory period at a regular price of US$250.

My suggestion to beginners is to hold off until you're sure that such a tool would be worthwhile for the specific work you do.

There are work-arounds. Those that I've used took more time and were considerably less convenient. As with a lot of tools, this one was born of laziness - and (almost) by accident.

[myxpykalix]

I haven't asked much because i felt you didn't want to divulge much about design, ect. which is understandable. But since then a few others questions have popped in my head.

The process i go thru now is, I do a C3 and zero my table. Then i manually move the carriage to the spot on the material that i want to zero it to. I copy those X, Y coordinates down then zero the X,Y. Then I set the Z. Then i'm set to start my file.
Now how many of those steps do i eliminate by using your device? I don't do much sheet goods and i'm not a production shop so for me i would have to decide how much the convienence of eliminating (X) number of steps would be worth.

I can tell you as an example with another tool called a Ringmaster in order to get exact angles on our rings for bowls you needed a tool that a guy invented called a "Precision angle guide" that was no more than 2 pieces of metal half lapped to look like a Cross with a thumbscrew and moveable pin and it was no more than 2" in size and the guy sold them for $50.00.
That example was to illustrate that it was a extroidinarily simple design and overpriced for what it was but underpriced for what it did. With that and some mathimatical equations you could make some nice stuff.