Circuit boards are made thousands at a time and it is not hard to squeeze a small design onto some free space and just cut it out at the end of the manufacturing process.
A custom CNC job needs to have someone spend time programming the tool path, and the machine needs to spend time working on your piece alone since each machine can usually only work on one at a time.
You might want to do some research into CNC machining processes.
$100 for a tube is pretty normal.
Most places will charge a minimum price because it is a waste of their time for anything cheaper.
Local professional machinists may not laugh at you IF you pay them their prevailing wage for the task at hand. They know how much time it takes to machine something better than you. If you tell them you can do it “this way” they’re gonna come close to say, “Well, YOU can do it YOUR way, but this is the WAY I do it.”
Otherwise they’ll think you think their business is some kind of non-profit charity and on top of that you’re also a better machinist than they are. And then if you continue to take any more of their time the exit door is the next thing they’ll take you to. :laughing:
That is your best option if you have several custom parts you would like to make. 5 to 10 different parts (not the same) would probably cost what you would pay to get started making your own and it’s loads of fun. 
You seem to be into the field. “Circuit boards are made thousands at a time and it is not hard to squeeze a small design onto some free space and just cut it out at the end of the manufacturing process.” I think the same applies for Swiss type lathes, for example.
Again, what you say is definitely the main problem with a generic CNC machined prototype (that’s why I did not even think requesting a quote for a flashlight tube on the websites that I have found in the first post). But I’m not convinced this also applies for simpler parts… for example, I would not be surprised if a service such as the one I’m thinking about would exist for laser or waterjet cut metal sheets (the closest thing to pcb I can think about). Why can’t it be the same for simple turned parts (such as custom screws… or flashlight tubes )?
For example:
in the case of swiss lathes the “one at a time” problem doesn’t exist. As for the code, maybe I’m wrong, but for simple parts such as the ones we are talking about I think it can be generated by the CAM software with little or maybe even no human work.
Your video still shows the parts being made one at a time.
To make more than one at a time there need to be multiple machines running in parallel.
Also unlike PCBs the tooling and stock needs to be changed for nearly every custom part that is requested.
Using a 4” diameter piece of aluminum would be a waste if one parts needs to be 3.9” and another part needs to be 1”.
Another thing is that PCBs are mass produced at millions per day.
How many people are ordering small quantities of custom laser cut sheets of metal or CNCd tubes?
Basically either get your own lathe, and make the stuff yourself, using your own time, manually and at lower precision, or you pay the price to get a custom CNCd high precision part.
The only way to get both a CNCd quality part and low cost is if you order in bulk, and then the price for several thousand units will be cheaper per part, because it can be quickly manufactured as shown in that video.
Uhm… you are right I should at least give it a try… after all I don’t have to ask for an exact quote, just giving a phone call to 2-3 machine shops asking a generic question should be enough… something like “I know you usuallly do much more serious stuff, but would it be possible tu turn a tube in the 20 mm OD, 50 mm length range, threaded at both ends and if so what costs are we talking about in the ballpark?”
Don’t tempt me… I knew flashlights were an addicting and expensive hobby… but I wouldn’t have thought to jump from spending 10-50 USD to 500-1000 
Buying your own machine, you could make those parts for around 10 bucks depending on size and where you buy your stock.
Most machine shops I know of charge between 50 to 100 dollars a hour. And there gonna want specific measurements and thread sizes.
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You might try member CNCman, he could probably get you a close estimate of what would be the cost and what you need.
Ummm… I don’t think so. I had an estimate for two small parts (spinner button, and another similar sized piece) and was told by two machine shops that the guys they use (external) would cost $300-500 to make the file needed for machining. The cost of those parts to be machined would be a few hundred, at least, to setup for one part. Each additional part would cost a $5-10.
I think if all you are looking for is a bored tube with threads, no styling, a manual machine would be the best route. $100 sounds like a steal for a one off part.
PCB machining can use three type of tools: diamond saw, carbide drill or carbide mill. Saw and mill are usually one size only (once they put in place they work until they are worn-out). PCB shape is usually simple, it is made from flat sheet and there is very small probability that something would go wrong way and tool will be broken. Tools have fixed position (Z axis), if you provide pcb files - they dont require extra work, files can be loaded and machine starts milling.
Even simple flashlight parts may require many cutting tools. You have to spend some time to figured out how part can be made if you have simple 4-tools toolpost. Bigger machine can make life little easier but anyway in most cases you have to make changes in tools and their position after previous work. Even this dont garantee great precise, most critical places have to be measured after machining and this changes can be made after production of first prototype. Part and tool position dont have big spare place, you need to worry about touching non-working tools to the part. Most parts require two-side machining, if you dont want to have jaw marks in your job you need to use soft jaws (and yes you need to bore them to the size you will clamp). Even if you provide some 3d model, it wont shorten time required to setup machine for your part and this is the reason why you always will pay extra 0.5-1.5 machine hours if you want to make few prototypes on cnc lathe.
talking about flashlight tubes, probably even less… for most lights it should be possible to start from one of the 2-3 usd spare tube easily available, instead of starting from scratch from a standard raw tube… so one just have to cut it and thread it, getting anodization as a bonus
With a nickname like that he seems THE MAN 
I’ve read his presentation thread Hi from the Gulf Coast I’ll write him a pm to invite him to join the discussion
Thank kiriba and the all the other guys.
I’d like to point out the last part of my opening post
the CNC service is just one of the options… other ideas? most of all, I can’t believe I am the only one interested in custom tubes… except the ones that were interested and ended up buying a lathe
I’ve just did some brainstorming, I think it will be useful if I update the first post with other options one could evaluate… I’ll update it if someone has feedback or other ideas.
- This website its worth having a look at: https://www.machining-4u.co.uk/pricing_guide/ Seems like similar parts (aluminum or steel threaded tubes) are made for 30-40 USD shipped to Europe.
- Asking a local machine shop: cheap CNC machining service for short tubes etc... similar to oshpark? - #11 by fedcas
- Starting from a cheap spare tube from the few models available and do all the work you can do by yourself, then asking a favour to someone working in the field. In my case the only problem is the threading… all the rest I can do by myself (cut it to size, cut the oring grooves, turn the portion to be threaded and make the relief groove).
- As above, but figuring out a way to cut the threads with some DIY… should not be impossible for soft materials such as aluminum… or maybe even some polymeric material with a copper sleeve for the electrical contact (water pipelines might be a ready made option having already the aluminum layer). Ok, this last one sucks: if the material is soft enough, maybe it could be even possible to screw it in place and make a “self tapping tube” (the material has to be stable enough with the temperature to not detach when the head gets warm).
- As above, but turning the aluminum tube and press fitting/gluing a plastic sleeve at both ends.
- As above, but turning the aluminum tube and press fitting/gluing a molded threaded part made in some misterious way (some resin maybe).
- As above, but 3d printing the sleeves (or the whole tube) and then smoothing the threads by hand (brushing/sanding/whatever)
…
This is a Video on cutting outside threads with a manual DRO lathe. Thread cutting on a lathe - YouTube
This is a 10 minute video showing the cutting process. Now whats left out is the 30 to 40 minutes of setup. Setting up the right gears for the threads specified (my lathe you have to manual install them) setting the right speed (mine has to have a belt pulley change) centering the piece if using a 4 jaw chuck with a dial indicator (this video appears to be a using a self centering chuck, since he only tightens one jaw) checking your start and finish points with the threads, finding and installing the threading tool on center. His also using a live center which takes another 5 minutes or so to setup. He has already turned the outside diameter down to the correct size to cut his threads (the time depends on how much material he had to remove to get to the desired thread diameter). Now the 10 minute video starts and you begin to cut threads and this is just the outside threads on one end. This takes a lot more time than one would imagine especially if you don’t double check yourself and end up screwing up and have to start all over again.
Just a little insight on how many processes it takes just to cut one thread, oh and I forgot to oil the machine up before I started.
Some of the newer more expensive lathes have time saving features that will reduce the time but it’s still a involved process.
Sooner or later Fedcas is gonna realize (reality) unless you’re family and close friends there IS NO FREE LUNCH nor FAVORS when it comes to professional machinists. :laughing:
There are a few options you can do, first, if there is enough interest in a particular battery tube of the same type of flashlight, then the cheapest option is to draw it upon CAD and I can try to help with a prototype to verify fit and functionality, then go to the manufacturer of the particular flashlight company with a viable CAD file and the number of tubes and ask if they are willing to make a small production run on them. They will be the cheapest option because they already have all the necessary equipment to do everything including anodizing, less the pcb boards for the springs and circuitry.
I will post a pic of a Haikelite 8 x 18650 extension battery tube for your info with dimensions so you can what is necessary to accomplish this first process. Give me an hour or so because we have the Grandchildren again tonight.
You could try 3D printing if you just want to play with how some different designs feel. But $100 for someone to use their years of experience in CNC, VERY expensive lathe, and hours of their time is a good deal.
What the videos don’t show you is experience and art that goes into making the chain of commands to build one part. Sure, once that file is perfected it can run fully automated for thousands of parts and get the cost way down. But it’s no easier to go through the effort to create that chain of commands and then use it only once. Unfortunately the tech does not exist to just plug a CNC into the internet and come back tomorrow to see what is piled in the bin. Very far from it.
My shop charges a $250 set up fee for a small part like that. Add material costs, tooling and man time. If you needed 1000…
If you really want something custom, you could try asking on Alibaba, as there are CNC services. If you are willing to provide measurements and a design sheet/CAD file, they would be willing to perhaps make you 10 tubes, but probably not less.
Here is an example of a partial dwg for a Haikelite MT series Extended Battery Tube for 8 x 18650, without tolerances, that is needed for a machine shop to begin planning. There can be a lot of planning involved prior to the machining process, available machine, tooling, material, programming, any engineering involvement, management, shipping & receiving, and supervision. The more of these entities that are involved, the higher the cost.
For a Machinist like me who is willing to help, can be restrained by the Workplace itself. I am not free to do anything I wish, but my last job I was given permission, even come in on the weekend and use the machines and scrap material. Finding these guys who are willing and have opportunity to do short production runs cheaply may be found on various Machinist Forums, I have never needed to search for this, but that is another option.
Our local Jr College has a 2yr Machine Shop Course and may do work like this cheap.
There may be some small independent or self employed shops that will take on jobs like these.
Full Machine capable shops will be expensive.
Keep looking.
I brought this up when I was looking for tubes myself. I never went through and asked. But check your local high school and community colleges in your area. At my local high school they will fix your car for free if you provide the parts so the students can get some real life practice. The teacher over sees everything and checks to make sure all the torque specs are right etc. Same with the machine shop they would make parts for people. It was all manual no cnc. But a high school or college has a nice sized budget yearly and won’t have the cost a private machine shop would. You could offer to buy the bar stock of metal and see if they would be willing to use their machines to give the students real life experience in machining like they will when they graduate and not just make the stuff the instructor has them make. All the upkeep and tools expense is in the yearly budget. They are cutting and filing metal down daily for different projects. They are going to go through there yearly budget or they won’t get the same amount next year.
Reminds me of being in the Marines when end of the year was coming up. It was spend spend spend, buy all the equipment ammo etc and go over budget. Because if we didn’t we wouldn’t get the same or more next year because they see it as not needed apparently.