First Mill Suggestions - mostly Stainless Sheet

[SPyKERMods]

First time poster, long time lurker.

So, I make custom design fan grills, like the PC modders used to use. I cut them out of either mirror finish stainless or better stock stainless to polish to a near mirror finish.

Currently, I pay a lot of money to have a larger laser cutting company cut and polish them. My last order of 60 ran about $1200. I can't afford that and neither can my customers.

I also cut similar "2D" polycarbonate shapes as block off plates, and have a few ideas for some smaller 3D parts which should be able to be done with 3-axis milling. A few could require additional 4-axis for mounting holes, but I could do that by hand. Most items are just over 80x80mm, however I'd like to be able to handle 140x140mm as well.

I have to stay inexpensive and move fast. Real cheap and real fast, like total under $1000 to start. New, used, kit...it's all open as long as it meets those guidelines. I hope the initial machine works well enough to show a profit and allow me to move up to something like a Tiag or larger within a year or so. I know that I will pay for the low start in time, but I don't need a high speed process with one-off customs and restock product...yet!

I learned about the MYDIYCNC kit through Kickstarter. With their updated spindle, and the right mill, I thought it might go the job, with the unit starting at about $600 assembled. I'ce combed the Classifieds, but most items seem to start at $1500.

Okay, hit me with the questions, flames, and all!

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[SCzEngrgGroup]

I cannot imagine any sub-$1000 machine being capable of cutting stainless at anything more than a positively glacial pace, if at all. Nor can I imagine a machine in that price range having the kind of accuracy or surface finish you'd probably want. It sure won't be anything even close to what you're getting right now with laser cutting. That is just not a realistic budget.

On your current parts, what portion of the cost is the laser cutting, and what part is the polishing? I'd be willing to bet the laser cutting is pretty cheap. If it's not, then you're dealing with the wrong shop. I'm making some laser-cut parts right now that are basically a 7.25" diameter circle with 36 "teeth" around the perimeter, a 1.5" center hole, four 45 degree x 5/16" bolt slots. 3/16" steel laser cut and zinc plated. They're costing me about $7 each, including shipping from PA to CA.

Regards,
Ray L.

Regards,
Ray L.

[SPyKERMods]

I cannot imagine any sub-$1000 machine being capable of cutting stainless at anything more than a positively glacial pace, if at all. Nor can I imagine a machine in that price range having the kind of accuracy or surface finish you'd probably want. It sure won't be anything even close to what you're getting right now with laser cutting. That is just not a realistic budget.

On your current parts, what portion of the cost is the laser cutting, and what part is the polishing? I'd be willing to bet the laser cutting is pretty cheap. If it's not, then you're dealing with the wrong shop. I'm making some laser-cut parts right now that are basically a 7.25" diameter circle with 36 "teeth" around the perimeter, a 1.5" center hole, four 45 degree x 5/16" bolt slots. 3/16" steel laser cut and zinc plated. They're costing me about $7 each, including shipping from PA to CA.

Regards,
Ray L.

Regards,
Ray L.

Polishing is about $3 out of the $20.

Here's an example of one:

[underthetire]

You will NEVER get that detail on a mill. 1/16 diameter end mill is probably the smallest you'd want to run, so any slot would have to be that size or larger. Cheap mill, low RPM and rigidity, and no coolant probably 3-4 hours minimum to cut anything close to that out. You'd better plan on 3X that amount just to get started.

[SPyKERMods]

Okay, so help me get real. What do I need, bare minimum, to set this up. The majority of the grills don't have this type of detail, but they do come in.

These are small run items, so that adds to cost as well when outsourcing, but I don't mind the setup personally when I do things like this because my dfx files are very good. Note, I also want to be able to cut polycarbonate and likely ABS plastic.

I just need more options than "This will cost you $3K to do". If I have to keep sourcing parts for now, I will but I have to find a lower cost and turnaround time. Maybe even someone on here who wants some extra cash?

Thanks in advance.

Sean
SPyKERMods

[underthetire]

Well, you could buy a benchtop mill and convert it to CNC yourself. 1200 for the mill, 500-800 for computer/motors/electronics. Weeks to get it all working. Then there is tooling/cam/learning programming. What options are you looking for? Someone to say, sure you can buy a 1K dollar router off Ebay and your parts magically show up?

[SPyKERMods]

Nope, not looking for smoke blown up my .... just a reality check, so I thank you.

So is $2K for a mill CNC conversion reasonable? And even if it takes weeks to build, I can deal with that as long as I can have production control once I learn the system. By building it, I will be much more knowledgeable about how the system works, so that is definately an option.

I have several friends, including a few on the site, who do this every day for a living, but none are real close physically to me. One suggested looking for a used Taig, building a flood tank and using a 1/16 mill like you suggested. I have extra PCs as IT is my primary profession, and modder is my second.

I will just have to promote a sale or 30 to cover the larger expenses, that's all.

So, on a more realistic level, what are the the forum's recommendations?

[691175002]

Realistically, you need a laser cutter (way out of your price range). A mill really isn't good for that kind of work.

If you try to convert a mill you are going to spend a lot of money and time, then realize you can cut only a couple grilles a day.

And you still can't cut proper corners so all your grilles will look silly.

[wizard]

First off if those are fairly thin gage stainless I wouldn't even consider doing them on a mill. This really is a job for a Laser or possibly a water jet.

As to your cost I'm not sure how they get $20 bucks a piece out if you, that seems to be extremely expensive. I can't imagine the parts taking more than a couple of minutes on a laser. So even if laser time is $120 an hour you are talking $4 a piece. Most companies would throw in a setup charge which might be $500 so we are at $580 plus materials. The polished stainless isn't cheap but on the other hand these parts aren't huge. Now the secondary operations aren't free either so that has to be taken into account too. Worst case maybe ten bucks a part. Note these are wild ass numbers on my part but not unreasonable in my estimation. My job shop experience was from some time ago though.

Nope, not looking for smoke blown up my .... just a reality check, so I thank you.

I think the big reality check here is that a mill isn't where you would want to do such things. Even on a cheap ass conversion mill it would likely cost you even more per part. At best a mill might make it possible to do a bit of the work yourself. Or example you could punch the bolt holes your self. ( Interesing that I used the word punch there instead of drill!).

Your best bet is to shop around a bit and see about setting yourself up to do the secondary operations such a deburring. Frankly you would need such equipment even if you milled the parts yourself. When shopping around find out what sizes of polished sheet they commonly use. Like it or not they may be charging you for the entire sheet each time you order. So consider orders that consume an entire sheet of steel.

So is $2K for a mill CNC conversion reasonable?

Not at all. Further I'm not sure how a mill would help you with costs. Instead of going to a laser shop now you have to find a shop to shear a bunch of blanks for you. Then you need a way to fixture the blanks for milling. I just don't see a conversion mill as being the cheap solution here.

And even if it takes weeks to build, I can deal with that as long as I can have production control once I learn the system. By building it, I will be much more knowledgeable about how the system works, so that is definately an option.

This is certainly true. Such a mill may very well be usable for some of your other parts but even then I dont see you hitting budget.

I have several friends, including a few on the site, who do this every day for a living, but none are real close physically to me. One suggested looking for a used Taig, building a flood tank and using a 1/16 mill like you suggested. I have extra PCs as IT is my primary profession, and modder is my second.

It is a terrible suggestion in my estimation. Each piece would take forever and you would likely need a new mill or resharpened one for each piece. That is if you don't break or chip the mill in the middle of the cycle. Machining stainless this way is a ***** and is probably why flood cooling was reccomended.

I will just have to promote a sale or 30 to cover the larger expenses, that's all.

I would very much shop around with the idea of splitting the effort between you and a laser or water jet jobber. For one thing you would need the deburring and polishing equipment even if you got the mill. Depending upon the methods choosen this equipment is not a trivial expense. Get your experience here while developing plans to expand your offerings and capabilities.

So, on a more realistic level, what are the the forum's recommendations?

Well you see what my reccomendations are already. They may fly against the grain here but I just think it is foolish to try to machine such parts on a mill. Especially production quanities. Frankly I'm not even sure how you would fixture such parts in a production manner for milling.

Find a job shop where they are willing to work with you to find a low cost solution. I suspect your best bet here is to consume one sheet of metal at a time ideally with the NC code all set to go. Further take on all secondary operations yourself. I'm sure somebody running a job shop can chime in here but $20 a piece seems like highway robbery to me.

Other ideas are different finishes. I always liked brushed stainless steels myself. Or you may like the finish a vibratory bowl will leave. It might also be advantageous to use thicker materials to make processing easier. The thinking with thicker materials is that if you can run the part through a vibratory bowl, tumbler or whatever without deforming them, then the overall process might end up being cheaper. There are lots of trade offs to be investigated and for very low volumes the best solution isn't always the obvious one.

Consider finding a laser jobber that does a lot of stencil type work for the electronics industry. They would hopefully be more optimized for the processing of very thin gage materials. Frankly if you have ever seen some of the stencils these people make your products should be a snap.

Finally another option is chemical machining. These sorts of companies specialize in "machining" sheet metals and the like with Acids. This is almost exactly like the etching of circuit board in the electronics industry. Volume may be an issue but it is an alternative and is a good way to deal with artwork that is hard to translate into CNC code.

[cybrhick]

Sean, I know your price point, and I am pretty sure I have a grasp on your production rate. You can save a ton by doing these yourself. Yes, a lazer is fast, efficient, and clean. But in the grand scheme of things, you would benefit financially from doing these yourself if you can find the right machine, and the right tooling. Never be a cheapskate when it comes to tooling. Good quality carbide endmills running proper feeds and speeds will last. Our material is thin. This is not a major deal here. And as for tool radius... USE A FILE if ya need to. Don't make it more complicated than it needs to be.

[SPyKERMods]

Sean, I know your price point, and I am pretty sure I have a grasp on your production rate. You can save a ton by doing these yourself. Yes, a lazer is fast, efficient, and clean. But in the grand scheme of things, you would benefit financially from doing these yourself if you can find the right machine, and the right tooling. Never be a cheapskate when it comes to tooling. Good quality carbide endmills running proper feeds and speeds will last. Our material is thin. This is not a major deal here. And as for tool radius... USE A FILE if ya need to. Don't make it more complicated than it needs to be.

Steve,

Hopefully once you get your enclosure done, we can talk, I can buy you the right mill and send you the design files, and we can try a few on your machine, with me paying you for your services, while I work to duplicate the setup.

Possible?

Thanks!

[SCzEngrgGroup]

Do yourself a favor - Before trying to do this with a mill (which I think would be a complete waste of time), contact Tom Dolan at Dolan Steel tomdolan54@live.com, and get a quote. Tell him I sent you. I can guarantee he can make your parts for a fraction of what you're paying now, and his work is truly first-rate.

Regards,
Ray L.

[cybrhick]

I know Sean personally, so I know a fair shre about his business. One thing that might not be coming across, is that even though sean may be ordering a run of 60 parts, there may be as many as 25 different designs in that order of 60. So what may seem like a production run, is actually several 2-5 piece orders. His throughput is not such that he would be ordering more than maybe a couple hundred parts per year. This is something to consider when it comes to farming work out. If he can find someone who can do a great price, that's awesome. But I think his cost would be far lower if he ran these "as needed". JMHO

[SPyKERMods]

I have sent a RFQ to Tom. We'll see what happens now. Thanks!

[SPyKERMods]

Do yourself a favor - Before trying to do this with a mill (which I think would be a complete waste of time), contact Tom Dolan at Dolan Steel tomdolan54@live.com, and get a quote. Tell him I sent you. I can guarantee he can make your parts for a fraction of what you're paying now, and his work is truly first-rate.

Regards,
Ray L.

To follow up on this, Tom is now cutting the parts for me at a fair price, and even letting me supply him with material he normally does not stock. Really fair guy and great to work with.

[SCzEngrgGroup]

To follow up on this, Tom is now cutting the parts for me at a fair price, and even letting me supply him with material he normally does not stock. Really fair guy and great to work with.

That's good to hear. Yes, Tom is a wonderful guy to work with. If only all vendors could be so good.

Regards,
Ray L.