[nuplowboy]

At long last, I've begun the contruction of my first CNC router/dremel!

After giving it some thought and thanks to some folks from the zone, I've decided to slap together jgro's design for my first attempt. I can then use that machine to make patterns for aluminum castings to make a more durable version with potentially more range. It'll also let me experiment so I better know what the Aluminum machine should be. (what size steppers, lead screw pitch, spindle type, etc)

Work began on Saturday as I hacked up the MDF into pieces roughly the sizes shown in the plans. I say roughly because Home Depot did some of the cuts and let's just say I'll have to adjust a few dimensions... That's just one more reason to upgrade to a big-ol' cabinet table saw someday...

Today I slept in, then went to work. I was able to get the base and bed torsion boxes glued up. Then, I ran out of Gorilla glue. And, I got hungry. I'd post pics, but we've all seen MDF boxes!

More to come, I've got money in this thing, I'm committed now!

[nuplowboy]

Due to other commitments (work, basketball league) Nothing was done on the cnc project today. However, this is fortunate, because the quality of the work was poor.

With any luck, progress will happen tomorrow afternoon.

I do have a couple of questions...

1. What is the most economical (cheap) software for converting 3D CAD models (STL, etc) to G-code? I have found a couple and the best bet so far is MeshCAM (~$100) Are there others out there I have not run across?

2. Does anyone have a supplier/part# for a good, simple N.C. home/limit switch they've had good luck with? Again, since I'm...err "thrifty", I'm looking for low-buck but decent.

Thanks! More to come and pictures whenever I get something that looks less like a pile of MDF!

[ger21]

1. What is the most economical (cheap) software for converting 3D CAD models (STL, etc) to G-code? I have found a couple and the best bet so far is MeshCAM (~$100) Are there others out there I have not run across?

There site was down when I just checked, but STLWork was on sale for $75. Not sure if it still is, though. http://www.cadcamcadcam.com/ I believe there is a demo you can try.

Almost forgot. FreeMill. http://www.cncportal.com
It's free, but a pain to use due to the almost nonexistant options. Depends what you're making, though.

[nuplowboy]

Well, tonight there was some progress. All adjustment blocks are drilled and tapped. I also dug out the router to start on the dados in some of the parts for the Y and Z. MDF is a real pain in the rear. Oh well. Progress is pretty slow since after getting home I have to fire up the heater in the shop and let that go for an hour so it gets up to a decent temp.

Ger21... I downloaded FreeMill last night, and checked out the other. Thanks for the links, they look promising. The price for FreeMill is definitely in my price range although I will probably upgrade to MeshCAM or STLwork later.

A question about FreeMill. I was playing around with it today and it has bunches of options for postprocessing. I've been figuring on running TurboCNC or a similar program to feed the 3-axis controller from HobbyCNC. My question is, which postprocessing option in FreeMill gives me the G-code or whatever that works (best) with TurboCNC?

[nuplowboy]

Things are starting to look like a machine. After a couple half-days of workin' on it this weekend, I have the base, table, and gantry pretty close to ready. Below are pics of the base/table and gantry as they were last night. Today I finished up some of the gantry glue-up. I also painted the table and the underside of the base (hammered black on most, silver/grey for the working table surface) and started drilling parts for the X axis carriage. That work's about 75% ready for glue.

Also bought the ready-rod and pipe this afternoon, Will have the gantry on the base rails as soon as I machine the angle-iron to hold the skate bearings. I'm using steel for the bearing supports instead of Aluminum. This is partly for strength and rigidity. The other reason is laziness, I can cut steel easier with my chop saw and I can always weld the excess into some other project!

[stevec]

nuplowboy,
Looks Great so far!

You are building alot faster than I did. I am building the same machine for my first build and the mdf cutting and building is now done, now I am working on the smaller stuff like the backlash-nuts. It's intresting to know that someone else is working on the same project at the same time and going through the same pains. I will take a photo of mine today and post it here for your viewing. We may be able to help each other in getting these up and running. I am still unsure about software, motors and a controller. I was thinking about using the hobbyCNC kit. What do you plan to use?

Steve

[dwwright]

I built the same machine about a month ago. I used the hobbycnc board and 80 oz/in. motors, but I'd recommend either the 127 or 200 oz/in that he sells now. I started out with a AT power supply but soon upgraded to a 24 V that I found on ebay. I'm now looking at modifying a amp power supply to get 35 to 40 volts out of. JGRO's design has plenty of adjustment built in to make it accurate. I thought about doing the steel angle iron myself, but I found that the aluminum was much easier to mill with the wood equipment I have. By the way, I didn't install home/limit switches as I haven't found that I need them. I may wire a emergency stop switch eventually to the limit switch. Other than that, most of the stuff I mill is within the table limits and it doesn't move fast enough (10-15 ipm) to cause much concern.

Darren

[stevec]

dwwright,

Do you recommend getting the hobbycnc chopper driver kit for $79.00 or should I get the package kit for $120.00. It's a $41.00 difference and not sure if it's a savings or get the other parts locally. Also, should I look to ebay for the stepper motors or get them at hobbycnc as well? And where do I get the power suppy.

Thanks
Steve

[dwwright]

dwwright,

Do you recommend getting the hobbycnc chopper driver kit for $79.00 or should I get the package kit for $120.00. It's a $41.00 difference and not sure if it's a savings or get the other parts locally. Also, should I look to ebay for the stepper motors or get them at hobbycnc as well? And where do I get the power suppy.

Thanks
Steve

Looks like the kit is a good value. I spent $30 for wire alone, fans are usually around $10 - $15, not to mention the other power supply parts. However Old stereos (with high output) and old amplifiers are good sources for power supplies and you can sometimes find them at antique stores for a good price. Check around at an office park to see if they have any old telephone equipment, they usually have some 24v power supplies with them that would work also. I guess it depends on how resourceful you are and if you want to build the power supply. Dave's price for the motors w/the board are a good value and he would probably be more likely to support them, but he's pretty helpful otherwise too.

Additionally, the next time around I'll do the 4-axis board. I regret not buying it the first time as I'd like to setup for spinning some table legs and such. Although you can add another motor and plug it in place of the x or y axis.

Just my thoughts and ramblings....Hope this helps

Darren

[nuplowboy]

I already have a hobbyCNC kit with the 80 oz steppers from about a year ago when I got semi-serious about building a machine. I got as far as to build the controller and PC power supply and attempt the first aluminum casting. That casting failed back in August/September and sort of took the wind out of my sails. I got motivated again and with the weather, figured the MDF plan was the best for a first run.

As far as build speed, I'm not being nearly as picky with details as I would normally be. I figure a CNC router with bad accuracy (bad for CNC) is still way better/easier than me cutting out patterns, etc by hand. You can build a pretty decent piece of furniture with 0.031 accuracy! The next machine will be much more rigid (all aluminum) and stronger and will be built with better precision. I'll probably upgrade to bigger steppers for the next one too, so I can tackle the occasional aluminum part or go faster in wood.

[stevec]

Here is a few shots of my jgro special. The last photo is a cheap cutting board I got at Walmart (.99). I am building the anti-backlash nuts (try) with it. Not sure if it will work, I read someone on this board say it will.

Steve

[nuplowboy]

No progress Monday, very little today. I did paint the top of the base. I started fab on the angle iron bearing supports for the Y axis. As I mentioned, I went with steel. Drilling the holes was no problem, but then I got to the spot faces to recess the cap screw heads. Using a file wasn't very appealing (laziness kicked in) and I hated to take the grinder to it and get a less-than flat surface. Then, a solution hit me (chair). I know plan to weld the head of the cap screw to the inside of the angle iron. This will leave the outside ridge clean and eliminate the need to hold the head of the screw while tightening/adjusting. I tacked one in place to test the plan before retiring to the couch for Biker Buildoff. (Darn Discovery Channel really cuts into my hobby time!, American Chopper, American HotRod...) Problem solved...

[nuplowboy]

More progress on the router. The X-axis carriage is now in primer and should be black by this evening, maybe later with the Super Bowl and all... I have the pipes in the base and one of them is trued up sqaure to the base and ready for the gantry, which is also in primer and ready for paint. The other day, I tossed the parts together and had the gantry rolling pretty smooth and tight, even without spending any time on getting the rails square first. With a little more effort and Jgro's advice from the thread in the downloads section, The gantry should end up pretty good.

Pics attached: base painted with galvanized pipes, gantry primed, X-axis primed, and y-axis bearing supports primed.

[nuplowboy]

Gantry, X-axis, and Y-axis bearing angle iron in hammered black...

[nuplowboy]

With the gantry painted up, I installed the bearings to the angle iron, using a scrap piece of steel angle as a flat to set the bearings pretty well flush with the angle iron so they start out fairly consistant. I placed the whole works in on the Y-axis rails and paralleled up the one rail I removed to install the gantry. The gantry rolled pretty nice, with a little more resistance at the ends of its travel. At first it felt pretty slop-free, but then I noticed that in the middle 2/3 of travel, the gantry could be rocked a bit. I do need to work on the adjustments more to fine tune, but I'm beginning to wonder if 1" pipe can be found in 4' pieces that are straight... I pulled the rails out and put them against the edge of my 4' level (machined edges). There does seem to be a slight bow to the pipes (maybe 1/16" over the length)

A question for the group: any preferences/suggestions for dealing with less-than straight pipe (not bad, straighest pieces out of two stores). I've thought of a couple possibilities:

1. Orient the pipes bowed inboard so it results in more bearing preload in the middle of the travel rather than slop in the middle.

2. (this one's more work and $/time) Install a piece of channel iron or similar beam on the outside of the base assembly. Then use setscrews to push in on the rails (and maybe pull) in places to try to hold the rail straighter.

3. ($) I had thought about buying some cold rolled solid bars in 1 1/4" from a local steel house. I need to look at the standards for cold rolled bar to see what the allowable straightness tolerance is for that size. The diameter would be pretty dead-on, but it might not be much straighter than what I've got, depending on the piece I get...

Like I said, I do still need to work on the adjustments I have and see how good I can get it. I might be able to live with the arch in the pipes once it's all set up, but I thought I'd pick your brains about ways to work with it.

Thanks in advance for the ideas...

[yukonho]

I would choose door number 1.
My guess is that this will have the desired effects. The truth is though that 4 feet of unsupported 1.25" anything will bow, especially with that heavy gantry. Consider going with a shorter X axis, or supporting the tube/bar at least in the middle.
colin

[nuplowboy]

Thanks Yukonho. I was sort of leaning that way, mostly due to laziness!

I'm not too worried about vertical deflections due to the gantry. It's not very heavy and I don't think it'll get too heavy with the other 2 axis in there. The 1" pipe (or a close approximation for calculations sake) will only deflect about 1/32" each beam with a 100lb gantry and the 41"-ish span I actually have, and I don't expect it to get that heavy. Solid 1 1/4" cuts the deflection by about half that if it comes down to that. The biggest problem is the pre-bowed pipe, which I can make work for this first machine. Worst case, I'll have to "persuade" the pipes to be straigter :devious: Let's see, if I hooked it under that plate, and slid a cheater pipe over.... Well, let's hope it doesn't come to that!

[nuplowboy]

I have officially hit my first semi-major setback. The other night while working to dial in the gantry on it's rails, the adjustment blocks for the pipes basically gave up. A few had stripped out the 1/4" threads, which I half expected. I had installed threaded inserts for wood with pretty big flutes in those spots that stripped. Then, on of those pulled out of the MDF! So, I "quietly" turned off the heater, turned off the lights and went inside.

Now, on to plan A.2! I am about to head into town to get some foam. From that foam, I will make adjustment blocks. This of course, sounds insane untill I stick those blocks in some sand and pour aluminum into them. A little drilling and tapping, and I'll have some stout blocks to remount the pipes in and try adjusting the gantry over. It was getting frustrating when I'd measure and remeasure everything nice and square, then tighten up the bearings and have it roll about once then start rocking and/or racking. I'll eliminate the give from the ends of the pipe and see where I get with the middle!

Off to Home Depot, or Lowes, or Menards... depends on which one's the easiest to get to based on the traffic today!

[mvaughn]

Making alignment blocks out of aluminum will definitely solve your issue.

What I did was to put T-nuts in my MDF blocks. It doesn't rely on MDFs ability to hold a thread. As long as the block doesn't break in half it should be just fine.

Just my $.02

Here is a pic:

[nuplowboy]

Got some foam and cast the adjustment blocks this afternoon. Actually, they're still cooling down. A little grinding, some holes, some threads, and I'll be back on track.

The castings didn't turn out perfect. There are some voids and shrinks on the back sides of the blocks, but I started with 1 1/2" foam, and they are solid and full for at least 1" of that, so there's plenty of metal to hold a couple pipes! Normally, I'd be upset about the quality, but this was a quickie pour with runners and sprues that were poorly thought out and poorly executed. Then I poured too slowly.

"Huskerplowboy Foundry: Specializing in small, poor quality castings."

Disclaimer:
By the way, metal casting is dangerous and shouldn't be done by anyone, anywhere, at any time. Just because I'm an idiot and play with very hot fire and metal, doesn't mean it's safe or smart. I cannot be held responsible for anyone trying casting themselves. (flame2)