dkj4linux
Elite member
Outstanding, Mike. You're practically there! That's a great looking setup you have and I'm anxious to see it in action. -- David
Cutting foam sheets... with a needle!
- Thread starter dkj4linux
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Outstanding, Mike. You're practically there! That's a great looking setup you have and I'm anxious to see it in action. -- David
wire10ga
Member
So this on the $150 laser post over the weekend. I'm getting ready to pull the trigger on ording the parts for the MPCNC. Thanks for the post and new thread. I'm sure I'll have some questions once I get started. One question though, can you use this for the 50% score cuts on the $tree foamboard?
It's cnc so you should have full control on the z axis. All you need to do is determine the depth that won't touch the paper on the other side. I think you would only run into problems if your foam board wasn't lying flat enough over the area you wanted 50%.
dkj4linux
Elite member
Wire10ga,
The first approximately 4:50 of the video in post #1 of this thread is all 50% score line cuts... at about 4:50 the needle plunges full-depth to cut the outline. I place the DTFB "crown down" on the bed of the CNC and then use straight-pins, clamps, and/or weights to hold down the edges.
I think you'll find the MPCNC perfect for foam cutting. I actually did a MPCNC pictorial build log in posts #114-125 of my thread over on the RCPowers site... check it out (http://www.rcpowers.com/community/threads/mostly-printed-cnc-and-cutting-foam.18808/).
Please keep us posted on your progress
-- David
dkj4linux
Elite member
Jaxx,
It looks as though Mike is doing the bearing and needle like I did so I'll respond to this. The loop in the music-wire needle is formed around a "mandrel" (usually a drill bit shank) that is about 2/3 the OD of the bearing. It then springs back a bit when removed from the mandrel and, when fitted around the bearing, it's held in a shallow groove in the outer race by its own spring pressure.
Forming the groove in the bearing's outer race and fabricating the needle initially sounds like a big deal but it really isn't... it takes far more time to explain than to actually do it. -- David
MikeJM
Member
Exactly as dkj4linux described. I haven't made the groove yet though. I'm nervous about going too deep and ruining the bearing. I'm contemplating gluing a rubber sleeve over the bearing for the spring loop to hold onto. I have 2 bearings so if I mess up the groove I'll have a back up.
Yes I made everything you see in the picture. I actually built that computer several years ago also. Here is a couple pictures of my build.
Also, here is a link to where I got my plans. Note, these plans are some of the most detailed CNC plans I have ever seen. Best of all they are free. The plans give all the info needed to build and part #s, qtys and where to buy them. There is also a video series on building the CNC.
I did modify the plans by widening the x axis and shortening the y axis.
http://www.cncsidewinder.com/how-to-build-a-cnc-router.html
Sorry dkj4linux, I'm not trying to hijack this thread.
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dkj4linux
Elite member
Not a problem, Mike. I appreciate anyone who builds their own CNC. Mine are/were all really crude compared to yours - I've built about a dozen CNC machines over the years - and each required custom fitting of numerous parts since I tend to work out of my parts stash/junkbox as much as possible. The three MPCNC's I've built are the first that I've made with interchangeable parts.
The trick to grooving the bearing is to allow it to "free-wheel" against the cutoff wheel and use very light pressure. I usually don't allow it to stay in contact long enough to spin the bearing too fast; i.e. touch it, let off, touch it, let off... repeat. When a "scuffed" line appears, you've probably gone deep enough. It doesn't take much of a groove... there are not a lot of side-forces trying to pull the needle off the bearing. Virtually all the significant forces involved are in line with and/or parallel to the plane of the face of the flywheel. -- David
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dkj4linux
Elite member
That is so cool, Mike. I'm really anxious to see it on your CNC and cutting plane parts. I've checked out a couple of your plane builds... love your 200% Spitfire. You do beautiful work... just as you have here. Well done.
Something you may want to play with since you work with more than just foam... I've often wondered (just never pursued to any extent) whether harder soft materials -- balsa, coroplast, etc. -- might be cut with repeated passes of increasing depth, just like with a rotary tool. Most soft materials can be cut with full depth cuts, of course, but my few attempts to cut coroplast full-depth have only perforated it between the ribs and left a nice outline... but not cut it. I can't help but believe some softer grades of balsa might cut quite nicely. What do you think? -- David
MikeJM
Member
David,
I believe it would cut soft balsa just fine. I'll try it sometime and give you an update.
And thanks for your kind words, I like building as much as I like flying.
dkj4linux
Elite member
Amen, amen! I also get a bigger kick out of building stuff than flying... actually more. Going-on 70 years old, I've resigned myself to the fact that my old spastic/shaky thumbs and easily confused/disoriented brain are not realistically going to improve and ever allow me to fly worth a flip. I have a fishing/flying buddy who flies much better than I do so I usually just build what I want to build, to see how it goes together and what it looks like, and then I give it to him to fly. I do get a big kick out of seeing them in the air but, for me, this CNC stuff gets what little attention I can afford to give
I look forward to seeing how your needle cuts balsa... and some of the other materials being commonly used by RC folks... EPP, balsa, coroplast (yikes!), etc.
Did you lightly touch the needle to a stone and make a short pencil point? I noticed early on that if the point is not symmetric all the way round, it'll cut better in some directions than others. It'll also insure that little/no debris is generated while cutting... a blunt tip will blow out the bottom side (big exit wounds) and leave a bunch of debris on the table. -- David
Some excellent stuff showing up here David!
I can't fly LOS worth anything but since I used to fly in two of flying club planes back in the early 80's (one high wing and one low wing) belonging to "that Company we worked for" and a friends 140 Cessna tail-dragger (N77007) I can handle FPV flight with no issues at all. I build way more than I fly too.
Thurmond
I can't fly LOS worth anything but since I used to fly in two of flying club planes back in the early 80's (one high wing and one low wing) belonging to "that Company we worked for" and a friends 140 Cessna tail-dragger (N77007) I can handle FPV flight with no issues at all. I build way more than I fly too.
Thurmond
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Wow, this is exactly what I want! But it seems that you can only buy the imperial version of the printed parts, is that correct? I don't have a 3d printer...well, maybe this is the reason to get one.
Instead of 200$ for buying the parts, I could put that towards a 3D printer I guess. Maybe a printrbot simple? A little pondering to do =)
Instead of 200$ for buying the parts, I could put that towards a 3D printer I guess. Maybe a printrbot simple? A little pondering to do =)
I'm thinking of getting this:
http://store.quintessentialuniversalbuildingdevice.com/product.php?id_product=144
so that I can print the parts for the Mostly Printed CNC. Is a printbed of 100X100X125mm enough for all the parts?
http://store.quintessentialuniversalbuildingdevice.com/product.php?id_product=144
so that I can print the parts for the Mostly Printed CNC. Is a printbed of 100X100X125mm enough for all the parts?
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