After running a job that cuts out a little more than a dozen of these things and thinking about the process, I’m likely going to alter it a little for the next run. I think it may be a little better to do a 1 mm run on the first pass (waterline and pencil only), run my rounding pass, and then finish it off with the same settings as the first pass but cut all the way through. My only question in doing that is that I must ensure that the waterline leaves a little material before pencil finish. I don’t think the adhesive will hold the parts to the table for a pass where it isn’t still held to the stock with a little thickness. I have read that waterline usually leaves a little material and doesn’t go all the way through, but the word ‘usually’ bothers me.
Are you running the G-Wizard fine finish? That gives glass like finishes very slowly.
My ‘fine finish’ pass is more between fine finish and finish. I basically split the difference to gain a little speed. Fine finish in G-Wizard has me at 1.1 IPM and .3 plunge. I don’t need it THAT badly!
Here is one suggestion: Why use a 1/16" end mill when all you’re doing is a cut out? Use an 0.125" and go much faster!
I can’t use a 0.125" size unfortunately because my gaps are ~1.7mm. The Onsrud mill I’m using is 2" long. I’m curious if they make a 1.5" or 1" version so that I could have less stick-out. According to G-Wizard that would allow me to speed things up nicely. A 2" length will not shove up into the Nomad’s spindle enough to leave much less than 1" stick-out.
I can’t use a 0.125" size unfortunately because my gaps are ~1.7mm.
Gotcha.
The Onsrud mill I’m using is 2" long. I’m curious if they make a 1.5" or 1" version so that I could have less stick-out. According to G-Wizard that would allow me to speed things up nicely. A 2" length will not shove up into the Nomad’s spindle enough to leave much less than 1" stick-out.
OUCH! That 2" length is a real deflection challenge… anywhere. Not just a Nomad challenge.
You don’t need to buy a shorter end mill… you can shorten it yourself. Cut off some of the shank. Warning, tool steel is, by design, tough stuff, so takes a while to cut through it.
When I have to do this I take a Dremel with a diamond covered wheel and shorten the end mill to my liking. A 0.125" end mill will do in one diamond covered wheel - ~US$1. I don’t do this often so I can live with that.
One can do this with a good hacksaw - manually - but one has to enjoy the sweat… it’s tough going.
I have a Dremel with said wheel…for some reason I didn’t think of hacking it off myself. I don’t like torturing myself so I’ll let the Dremel handle it. That alone will give me a lot of wiggle room in G-Wizard. Thanks!
I have a Dremel with said wheel…for some reason I didn’t think of hacking it off myself. I don’t like torturing myself so I’ll let the Dremel handle it. That alone will give me a lot of wiggle room in G-Wizard. Thanks!
Eye protection! Lots of sparks and the piece cut off can go flying.
I’m curious. For this sort of part, would a laser not be a better option? You will get superior accuracy, a pristine edge finish, and each piece would take about 5 seconds of time to cut. From the picture, I don’t see anything that would require a mill/router operation. Obviously, you already have the Nomad…but if your volume of production over time is high enough, it might make sense to add a laser cutter to your set of equipment or find a local makerspace and cut sheets of these things at a time.
If you’re interested, I can cut a sample of your design on my laser and mail it to you (no cost) so you can better evaluate your options for this particular model. I’ve got some free time, so I’d be happy to do it.
Laser cutters are perfect for this type of job. Just be sure to have safe air handling… plastics generate carcinogens, teratogens, and toxics when lased. It’s a considerable more difficult challenge to keep the air safe than with CNC machines.
@CraigTheFabricator I was actually very close at purchasing a laser cutter instead, BUT I went with the Nomad since it was the healthier and less costly to maintain option. I don’t have a very good way to ventilate a laser cutter, the cost was much higher than the Nomad for a reliable cutter, and I didn’t like what I had read about the life of the replaceable items.
I know laser would be a perfect fit for this job and I may invest in something like that in the future, but the Nomad gives me versatility that I would not have had with the laser cutter for some of the projects that I have on my to do list. Having someone else do it for me may be an option, but I sort of like the idea of having complete control over the design, manufacturing, and sale.
I would love to be proven wrong that you can’t get a decent reliable laser cutter for less than $6k.
You’re also learning machining and there are many things left to learn. We’re here to help. We can get the machining time for parts like that down quite a bit. Not to laser cutter levels, but pretty close.
The GlowForge:
… seems the be the one getting everyone excite right now. Well below $6K but air handling need to be thought threw.
Air handling is definitely an issue…particularly when working with plastics. To avoid venting the fumes out into the atmosphere and annoy the neighbors, I went with a BOFA AD1000 laser extraction system (http://www.bofaamericas.com/productDetails.asp?pid=46)
Not cheap, but by the time the air makes it through all the filters and into the room it’s probably cleaner and more odor-free than the air that got sucked in. It’s definitely worth it for keeping all that crud out of my lungs.
@mbellon I looked at the GlowForge A LOT and really like it…if it comes true. I couldn’t stomach giving a company that much money for a product that offers so much for so little and was over a year away from me getting one in my hands (after paying for the entire thing). I felt overly uneasy about it and still do.
The BOFA AD1000 is good choice. Also remember that filters wear out and need to be replaced - they don’t last forever (or even close).
Safe air handling for lasers is a good deal more difficult than CNC machines… CNC machines don’t generate the chemically active stuff to any extent. On the other hand, we do have that nasties in the sap of the wood, the wood itself and viruses (particularly in the exotics and tropicals).
CNC airflow is probably a good deal higher than with laser cutters since the vacuum is often also used to pick up large particles.
If CNC particles are dangerous, laser cutter particles, gases and fumes (carcinogens, teratogens, and toxics) are CONSIDERABLY MORE DANGEROUS.
Keep in mind that @dyelton is just learning machining details. There is a lot of room to go MUCH faster.
The lesson learned the hard way - fought for - is the one that will valuable for the rest of ones life. As things progress, the machining time will come down dramatically… with awesome finish.
No, not laser fast, but a laser isn’t going to cut full 3D shapes either. A fully equipped shop today would have a CNC, a laser, and a 3D printer. Of the three, the most versatile is the CNC, albeit one of the slower (slowest) solutions. On a budget, many go the CNC route. 3D printers aren’t there yet but the gap is closing. For 2D work, can’t beat a nice 40+W laser cutter.
You can easily make those edges look like glass if you vapor polish them. I use methylene chloride by boiling it in a flask and using a rubber tube to direct the vapor to the part. You have to do it in a well ventilated area but it give you very good control and would only take about 10 seconds to get the edges on that part looking like glass. It works very well on acrylic and polycarbonate. You can also use a torch flame to do the same thing but I’ve had less luck using that method.
…is a chemical that I would go near if you paid me. It is highly volatile, flammable (which generates Phosgene, a nerve gas), metabolizes into the CO pathway and can cause sudden, catastrophic loss of consciousness, suffocation and other nasty things. It is banned outside of controlled industrial uses in Europe and is under review here in the US (way overdue).
It’s a wonderful paint stripper and I imagine that’s why there is such resistance to not removing it from common use.
Anyone working with it should read up on how to safely working wth it… or better yet, find a safer alternative.
I was really excited about the Glowforge until I saw this in their faq:
“Does Glowforge need a wifi connection?
Yes, many of the coolest features of Glowforge are possible because we are running software in servers hosted in Google’s data centers.”
I have always had a healthy skepticism towards cloud dependent devices. They are popular with venture capital guys because they create an ongoing revenue stream but create concerns in my mind regarding privacy, security of intellectual property, and longevity/dependance.
The Revolv hub’s irresponsible abandonment by Nest (Google!) is a good example. The Revolv was an expensive IOT hub. When Nest acquired the manufacturer, it was because they wanted the human resources they had, not the product. It is one thing for Nest to abandon further development of the product, but quite another to shut down the servers that made this cloud based product work, and that is what Nest has done.
From a PCWorld article: “As of May 15, 2016, Revolv service will no longer be available. The Revolv app won’t open and the hub won’t work,” the company said on its site. All Revolv data will be deleted.
Nest (Google, er, Alphabet) could well afford to keep a server running to support this product, at least for now. At the very least they could open source the product so the community could keep the service alive. They simply appear not to care about screwing Revolv owners.
That is why I avoid cloud based products like the plague. Clouds are made up of nothing but vapor and dust. “The cloud” is no more substantial than clouds.
I did this today with my Dremel. Holy cow I didn’t realize how tough it would be to cut through! I wouldn’t want to do that very often and absolutely would never want to do it with a hacksaw. No. Way.
BTW, so far (including hacking off half an inch of the Onsrud cutter) I’ve been able to get my time to under an hour for the job that was previously taking ~3 hours in all. I already know of more things I’ll do on the next run that should get me down to ~40 minutes.
I’m now using a Onsrud 63-701 instead of the 63-751. The 63-701 is chewing through this acrylic like nobody’s business so I think I could push it just a little more. I’m keeping my deflection under .0005 knowing that the Nomad can’t do better than .001.
I really appreciate everyone’s additions to this thread. You have all been very helpful for this noob (me).
I did this today with my Dremel. Holy cow I didn’t realize how tough it would be to cut through! I wouldn’t want to do that very often and absolutely would never want to do it with a hacksaw. No. Way.
I. Did. Warn. You.
Seriously, machine steel rivals armor steel in toughness.
BTW, so far (including hacking off half an inch of the Onsrud cutter) I’ve been able to get my time to under an hour for the job that was previously taking ~3 hours in all. I already know of more things I’ll do on the next run that should get me down to ~40 minutes.
Excellent! You’re on the way! With increasing experience you’ll be able to select machine tools and set feeds and speeds very close to optimally on the first try.
I should warn you, however. Tuning machining can become an obsession. At some point, you’ve got to walk away and say this is good enough.
I’m now using a Onsrud 63-701 instead of the 63-751. The 63-701 is chewing through this acrylic like nobody’s business so I think I could push it just a little more. I’m keeping my deflection under .0005 knowing that the Nomad can’t do better than .001.
As I’ve said many times, Onsrud end mills are a work of art. Worth every penny.
Acrylic is a funny one. Some call it hard, others soft… or softish. You’ve obvious got the right tool fo the job and hard it is.
mark
P.S.
Onsrud machine tools are expensive so be sure to carefully put them away in their containers when done. Don’t let anything mar the artwork!
It doesn’t sound like it, but if you’re still having holding problems, have you thought about milling out 60-70% of a row of them. Then using a long shallow clamp, or multiple clamps to hold part of the already cut section of the parts down, and then cutting out the rest? You’d lose a little time due to loading a second file, but you’d likely save time by being able to cut out a row of them at a time.
Someone with more experience I’m sure could fine tune the details, but I think the overall concept could work?
Second thought. why not do this process through mold making? It’d cost you some money for a vacuum chamber. but you could do whole sheets of them at a time. A vacuum chamber is far less than a laser cutter as well. Also each part would take longer depending on your set times, but it is all idle time that could be spent doing something else? I haven’t done the research on the numbers, but I’d be surprised if it wasn’t a cheaper route after the negative was made, and you’d only have to mill at single digit speeds once to get those glass edges.
I found a way to get things to hold until the last cutout, it does require three runs though. My pieces have cuts around the entire piece and milling takes place inside as well. They are also so small that no clamping is possible. I’d either need to vacuum hold or do what I’m doing which is hold down with double sided tape (seems to be working now that I’ve tried a few different tapes and methods).
I have thought of this yes, but I’m pretty sure I can’t keep the accuracy within needed limits by doing it this way. We have many of these machines where I work and I’ve talked a bit with the plastics supervisor about methods. He has told me that I would not be able to get the accuracy needed without a lot of experience and more expensive machines. I’m satisfied (at least at this time) with the current method, particularly since I know I can cut my time down a little more even.
I know you’re all set with your hold down system for these jobs, but I wanted to make sure you’d seen this cool custom vacuum spoilboard someone made for their Nomad a while ago:
Love that thing. If the tape approach ends up not working out, maybe you can design something along these lines. Hopefully this will not be necessary, but just in case…
