- January 4, 2018 at 5:07 pm #50509
I’ve been working on a small form factor computer case design and figured it would be quite helpful to have a CNC. Originally I was looking at an MPCNC, but I found I could drastically lower the cost of the case if I make part of the case from a strip of aluminum and bend it into a U-shape. This design, however, would require at least 1200mm of space in one direction, so I am looking at 500mmX * 1500mmY * 50mmZ, which the MPCNC would not be stable enough for, correct?
How precise would the LowRider be at this size? And would I need anything in addition to what’s in the kit? Obviously, I know I need printed parts, flat stock parts, 25.4mm OD stainless rails, and a spindle.
Thanks in advance.January 5, 2018 at 5:11 am #50527
Your length is less than the width of my lowrider. The size you’re looking at shouldn’t be a problem. Cutting the aluminum will be the biggest headache for you. Aluminum can be tricky.
Off the top of my head, probably the easiest way to cut it would be using some 1 inch foam insulation, or something close to that in mm, not sure how it’s measured in the rest of the world. Use double stick tape to stick the aluminum to the foam. Then use a down cut bit all the way through the aluminum so as it cuts it pushes the aluminum down against the foam. Feeds and speeds will have to be an experiment on some scrap first to find out though.January 5, 2018 at 9:19 am #50535
I do think the LowRider is the better choice, it should cut something that size better. Once you dial in your feeds and speeds like Barry says it will be a pretty easy to deal with. Make the machine as small as possible for optimal results.January 5, 2018 at 4:48 pm #50556
I’ve also been considering sand casting the basic shape of the part instead and then CNCing that, but I would need to have 100mm of Z travel, which is over the 3 inches max stated on the product page, but if I go this route I could keep the Y to 500mm. In this case, an MPCNC would be the better choice as it can handle more Z travel, but if the LowRider could handle 100mmZ at such a small size, which CNC would yield a better degree of precision?
I’ve embedded a picture of the current midframe design because I can’t quite figure out how to put it into words. This is by far the most complex part in the design, everything else is just 2mm thick sheets.
Attachments:January 5, 2018 at 5:08 pm #50560
So you want to make all of that out of aluminum, and the original idea is to make a seem, unwrap it, lay it flat, mill it, bend it into shape? I really don’t see any other way to do it except make corners and have 4 smaller pieces. That is a ton of cutting though, can you make any of that out of an easier material to work with?
If I am following correctly on the casting idea, how would you mill 100mm deep? Max on wood is about 1.5″ unless it is a very shallow curve.
Why not the LowRider, it really is the best option for big material? To answer the original question, it is exactly as accurate as the MPCNC, same exact parts, same exact firmware, same gcode, one axis is just a table so it can be as large as you need it.January 6, 2018 at 7:58 am #50603
I could always use an easier material but with that comes loss of structural integrity and/or increased size.
On the casting idea, there were two possibilities. First, if I can make a casting good enough that it would only require a bit of cleaning up to remove the leftovers from the gating system and taper, then I would only need to mill 50mm deep as I could mill from both sides. If I end up not being able to make a good enough casting, I would instead cast a square shape with a void in the middle, and then CNC from there.
However, this option, while still only requiring 50mm milling depth, would require 350mm Z height so now MPCNC would be the only choice.
I guess the best option is to go with an MPCNC at first and if I end up needing something bigger I could always build a LowRider.January 6, 2018 at 8:21 am #50611
Still you can’t really 50mm deep on a flat wall.The collet will hit after about 30mm. But I don’t know anyone that has done more than about 10mm in aluminum, that is tough.
The lowrider can be as tall as you need it to be, same rules apply to both, a drop table is a good solution as well on either machine. Either one you make you want to have minimum z length to keep rigidity for aluminum.January 6, 2018 at 8:23 am #50612
You mean bits long enough don’t exist and can’t be made?January 6, 2018 at 8:33 am #50613
Not really. The diameter would need to increase, then the HP would need to increase to drive it, the the rigidity would need to increase to handle the torque of a larger diameter.
The bits we use have about a 10mm depth, the 30mm I am quoting is a wood bit I mentioned earlier. 30 would be pushing it to the extreme and I do not think it would work in metal.January 6, 2018 at 8:34 am #50614
Hmm, well it looks like bending’s my only option then. This oughta be fun.January 6, 2018 at 8:39 am #50615
Rigid corners and 4 panels with really nice hardware would look nice and industrial and be super strong, bends are pretty hard (for me at least) to get accurate.
Please don’t think I am picking on you just this sort of this is extremely interesting to me. This is exactly what I have done my entire (short) engineering career. Not only do you have to design a slick part you have to make sure it can be manufactured. So when I see projects like this I go into problem solving mode. That and I want to make sure you have an enjoyable time with my creation and understand it limitations and strengths.January 6, 2018 at 8:42 am #50616
Yeah, I might end up going that route too, but I’m not 100% sure about the industrial look.
I would have never thought you were picking on me, you’ve been nothing but helpful!January 8, 2018 at 9:42 am #50704
To add to What Ryan’s already said maybe you could make dies out of hardwood and use bottle jacks for compression and then just cut out the individual sheets on your CNC lay it in your dies and form your parts that way. You might need to anneal aluminum first.
1 user thanked author for this post.January 12, 2018 at 11:56 am #50919
This wouldn’t be nearly as fun (way less work), but you could use the internals of just about any existing pc case and simply cut your aluminum panels to apply to the outside.
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