Answers to some questions

[KeithB]

Been so busy I haven't had time to respond to a couple posts so I thought I would do it right now.

To Pistolero - My carry gun is an Airweight 642-2 S&W with CT lasergrips. The grips have the S&W logo on them, I got the gun used, I believe it was some type of special offering in conjunction with the NRA. The activation button is in the front of the grip under the middle finger. Very convenient and as foolproof as can be had. The grips are harder rubber than Pachmyers but soft enough and with a good feel to the surface.

Someone posted about machining Teflon rod and asked if $150 was a fair price? I will explain what the machinist/shop owner sees and let the poster determine the fairness of the quote.

1. How fast do you want it? I do a lot of jobs for a low cost IF the one-time customer is willing to let me work it in between other jobs. Want it tomorrow? If I have to tear down a setup and switch to a different chuck and change out my tooling you're going to pay.

2. Hanging on to some plastics to machine them is tough. If it is a rod then a collet might work, but remember PTFE (Teflon) is soft and slippery, it doesn't want to be grabbed. If I have to make a special collet or set of soft jaws to hang on to your part without marking it up then you're going to pay.

3. Some shops are tied up with their existing commercial customers and don't have a lot of capacity left over to do one-off jobs for folks that they may never see again. As much as I recognize that old customers were all new customers at one time and that that is how you grow a business when I'm in the middle of running a 1000 piece order worth $4-$5k and somebody I've never seen before and probably will never see again drops in with a small job that they want yesterday - well, you're going to pay.

A machine shop is going to charge $50 -$100/hr or more depending on their equipment base and overhead. Even the simplest on-off job can take an hour or more to set up and run, and any special tools, etc needed add to that.

So was it a fair price? You decide.

 

[smokeywolf]

I remember machining film rollers from UHMW Polyethylene. Material had be frozen when it was machined or it got too gooey and produced false measurements. Those were some expensive film rollers.

 

[Ian]

"Organic machining", you guys who've worked with squishy, slippery, amorphous materials will apprecate this:

 

[Ian]

This just in, two month wait, obsolete part for a hydraulic pump drive from 1978, custom machined to order from an engineering drawing I had to get late at night from a man in a suit in a dark alley behind an Italian food joint (well, maybe that's an exaggeration but not by much!).

It's about 6" long, anyone wanna guess how much it cost?

 

[Pistolero]

My guess, Ian is that that is about at $1500 part, maybe more. Splines are a PITA without the right
broach in stock.
If the shop was set up to hobb gears, it could be significantly less.

In production work, that part might sell for $300 or so, unless it says "Deere" or "Caterpillar" on the
box....

 

[Pistolero]

Thanks, Keith. The ones I see advertised say hard plastic, sounds pretty uninviting. The idea
seems really good to have a laser on a snubbie, esp at night.

Bill

 

[tinhorn97062]

It's about 6" long, anyone wanna guess how much it cost?

View attachment 9545

Assuming it’s a common stainless alloy, I’m probably looking at close to $10k in that picture. Added 20% if it’s an exotic alloy.

 

[Pistolero]

Looks like CS to me, but hard to tell by looking, esp in a photo.

 

[Ian]

Yes, CS. 4140 to be exact. Our bill was $4,500. I'm pretty sure the splines were hobbed in two separate operations with a good bead-blasting of the first set (left in the pic) before hobbing the smaller set and then off to the lathe again for some final polishing of bearing and seal surfaces.

 

[smokeywolf]

The splines are expensive as all get-out and OD bearing surfaces typically demand at least an 8 micro surface finish and a dimensional tolerance of +.0000/-.0002. High surface finishes and tight tolerances cost money; even when done on a cylindrical grinder.

 

[Ian]

I bet they finished it with sandpaper, but it's bang-on spec, both sides. The seal surface finish is what I was concerned about. There's unfortunately no spec on the finishes for either so I told the shop to do the "usual" for press-fit bearings and high-speed nitrile, garter lip seals. Looks pretty good to me.

 

[Brad]

You didn’t make that yourself Ian?

Keith, I never considered the cost of tearing down and existing setup then redoing it after a small job is complete.

Small jobs are a pain for most shops I bet.

 

[Brad]

Best way to avoid paying $150 for one? Order 1K at $75 each.

Economy of scale can work in your favor. If you need enough.

 

[Ian]

From what I hear, being a "job shop" doing onesey-twoseys all day is about the lowest-profit model a machine shop can have.

 

[Brad]

And that nice turning center of Keith’s is kinda wasted on one offs. A run of multiples is where it really shines.

 

[KeithB]

Ian you're right on about that. Let's say I run a part that takes 10 minutes to machine. At $60/hr that part should cost $10, right! In our shop if you give me a little time I will run it between other jobs when most of the tools and workholding devices are in place. I still need time to get out the right measuring and cutting tools, and of course afterwards I have to write up an invoice and clean up the machine. All of this makes a 10 minute job into a 30+ minute job. That part is now $30 at the cheapest and that is with a time delay and having some other things be right.

That is for a job where you have all the tools and don't need any special fixturing. Imagine the overhead cost of having specialized tools such as gear milling hobs and broaches and similar. Doesn't surprise me a bit that Ian's part cost $4500 as a one-off item. And yes, if you were making 100,000 of them they would probably be $450 or less.

 

[Rick]

I'm kinda surprised it wasn't more than that. First thing I thought of looking at the picture was it'll probably be cheaper to retro fit the machine for a new and in production hydraulic pump

 

[Pistolero]

I only missed by a factor of 3....

Bill

 

[Ian]

The new model of the Smith-Berger four-pump hydraulic drive is 20 grand and has a metric ISO flange which would have to have a custom, metric mounting adapter fabricated to mate with the practically one-off PTO tower it mounts to. Worn splines was the only failure, pump drive is ok so it's much cheaper and easier to salvage what we had. Funny thing, the other shaft that mates with this one we already had made new and it was only $2800. It is about three feet ling and 2.5" in diameter at the middle with female splines in one end, threaded stub on the other, and three long keyways milled in. Six or seven precision bearing surfaces if different diameters and a press fit sprocket surface. I guess it was simpler to make due to only needing to be fixtured one time each in three different machines. The 13' of 4" Ramsey chain was spendy, too, and took six weeks to get.

 

[freebullet]

I'd have Lincoln locker'd it for 4500 lol.

I've had occasional need for same day machining. It's not cheap but worth it for a skilled craftsman. Last one cost me 300, took him about 1.5hr & my hub takes locally available bearings & fits great after his service. Totally worth every penny & we were up/ running the same day instead of the next for about the same money.