Group orders for custom etched parts?

[victor miranda]

12 x 18 inches is  18- 4x3 sections

the trick is how many sections per sheet
and how many sheets per run?

and we'd have to pay the person for all the logistical work.

hmmmm

well the post makes sense to me.

allow me an example

I want farm waggons and horses

and I can fit all that into a 4by3 inch section
and I want 5 of them for my layout

some one else wants to add walkways to a long grain hopper.

that means they will use two sections and have enough space
for making all the details for two cars

they want enough to do 20 cars

make up some more such things
and fill a sheet and make a run of 10 sheets

I'd end up getting 10 waggons... and paying for them.

I would be willing to buy extra to get on.

There are rights of ownership to the 4x3 tooling/art
to be considered
and how to finance...

It can be done, but all must understand being flexible is required.

victor

[TrainCat2]

Allow me to throw some wrinkles in.

Car walkways such as the ones I agreed to do for the two Trainman covered hoppers and the Maxi grating Gary wants are better done using .005" stainless steel. SS comes in 12 x 24 sheets, costs 20% more and the finish is not very good once half etched. Unlike brass, the texture of half etch SS is rough. So someone has to know the correct material usage for each project. Each project on a sheet then must have like specs (thickness & material). Each person doing the design must take design parameters into account such as adjusting for undercutting, min stroke thickness on lines, etc. Single pass vs double pass through the etcher.

Most etchers have a 20% allowance on any sheet failures and still consider the sheet as OK. IMPORTANT NOTE HERE!! When a sheet contains multiples of the same design, it's no problem. The rub comes when the entire sheet is one design (like a bridge) or contains different designs on the same sheet. The latter will affect someones yield while not affecting others. And yes, I HAVE had to throw out an entire sheet because one area of the sheet went bad and I needed 100% or nothing.

Also, concerning layouts on the sheet, the person doing it at the company may not care how tight the design is to maximize the yield. The layout designer must be willing to adjust the individual design sections for a placement that will produce a better yield. This will affect layout costs and ultimately, individual costs

Who will pay to have the sheet cut-up or who will take the time to cut-up a sheet? Having the etcher do it causes it own problems (section spacing, symmetrical design for the sections to allow for the cutter, etc). How about bagging the parts to protect them?

I am NOT trying to talk anyone out of doing this, but I want you to know what you are getting into instead of having issues smack you in the face later.

[victor miranda]

TrainCat2,

you are scaring me.
you are not saying... NO!

hmmm. 20 percent failure?

I be looking to re-negotiate that somehow....

frankly, I can't see this ever happening
because of all the variables.

I can tell you it would be a lot of fun to see
if it is possible to sell spots in a run

have you any way to estimate cost on a 3x4 section,

If I were to even attempt this,
I think I'd sell sections on a test sheet.

declare the parameters like thickness and material etc.
and take orders for space in the test sheet.

charge for artwork help....

making a profit may be a struggle in this
because I can see a BIG pain factor.

victor

[Chris333]

I think what Bob is saying is if the sheet is a bunch of different parts there is more of a chance for failure. Perhaps if the whole sheet is of the same 3x4" pieces the failure rate goes down. 

Ideally the metal would all etch away at the same rate, but it just doesn't happen that way. A metal running board might etch differently than a bridge side of half etched rivets, but a running board and a chain link fence might etch the same.

Again this is just how I see it. At home I just dunk parts into bowl basically. 

As long as you can sell the parts it is probably worth it. All of Bob's stuff I have looks great and I can't do anything close to it at home.

[James Costello]

That's what I thought too. Assuming we can get a sheet done one at a time, the minimum order for the run to go ahead would be however many of "design x" will fit on a sheet???

[TrainCat2]

I think what Bob is saying is if the sheet is a bunch of different parts there is more of a chance for failure. Perhaps if the whole sheet is of the same 3x4" pieces the failure rate goes down.

Yes, and yet no. Victor, you don't need to be scared by what I am informing you of, just realize that it is part of business and you WILL write off some/parts of sheets. I took some pics and made some samples to illustrate.

First is a sheet of the same small design replicated across the sheet. I used a blue blob to show a defect in the etch process that is well within the 20% allowable error. In this case, you would loose 4 out of the 88 pieces on the sheet. Acceptable loss.


Second is a sheet of six Towboats and a bunch of Z-Scale Industrial Ladders. I applied the same size blue blob and now I lost 2 ladders and 17% of my desired product. This sheet is now marginal. Had this been a shared sheet, the guy with the ladders would not have said anything. The guy with the towboat would have been very upset with his losses.


Real life disaster. Here is a pic of a recent sheet that has a 5% error that has rendered the entire sheet useless to me. I could not actually sell anything from this sheet and it will be used for spare parts. Again, the etch error is within the 20% allowable by the vendor before he considers the sheet a QC issue and re-etches a new sheet.



Re-negotiating the acceptable error rate WILL increase the costs per sheet dramatically. It's all a numbers game and you assume the most risk.

One more risk I forgot to mention, artwork errors. What happens if the artwork is incorrect for one of the designs. This will require a new artwork and a new $225 photo tool. Someone must pay for that. Costs add up REAL quick.

[GaryHinshaw]

GREAT examples Bob -- thanks.  Is it your experience (or anyone else's) that most failures are localized?  If so, there would be a premium on designing as small a unit cell as possible, which is the situation I was picturing.

Here's another example: in walkways with etched holes, I've seen plenty of cases where holes did not quite etch through, and the defect was relatively uniform over a full ~3x4 sheet.  If that had been the case over a full size sheet, would that qualify as a defective run by your vendor?  Is it common to argue over what constitutes a defect?  [Some of us are pickier than others... ]

-gfh

[Chris333]

Bob,
That sheet with the towers. It looks like the bottom sprayer just stopped short of completing the sheet. Is that it or was it just some anomaly in the brass sheet?

[Sokramiketes]

Few thoughts from my etching experience: 

Use PPD Ltd. 

No minimum order.  No need to find partners to fill a "standard" sheet size.  If they screw up, they etch more copies and send them all to you so you can pick through the good ones.  IE: I order 100 copies, I might get 120 because they noticed some defects. 

Quality is some of the highest I've seen, very clean parts.  And they are used to working with hobbyists.

If there's any downside, it's that it can sometimes take up to a month to get your parts if they have other larger orders in and you're looking for a small run.

[ednadolski]

Use PPD Ltd. 

Link: http://www.ppdltd.com/web_site_3/page_1_intro.html