[DeusExMachina]

Don't see too many of these around here. I've been slowly trying to build a cnc 'cutting tool' for a couple years now.

At one point I had built my own stepper controller and had a very ugly x/y table built out of wood with skateboard bearings, 3-18 lead screw and 51 oz-in motors....Yeah that didn't make it very far, but I continued reading and slowly saving up to start building something more useful.

A few months ago I bought a HF X1. I was looking for a little mill to play around with and well, it certainly was cheap. I've used it quite a bit over the last few months, not doing anything in particular just making little things here. Its limited capabilities make working on any mid-sized part an exercise in patience and endurance. It may be slow but its capable of what I would like it to do (at least for the time being).

Well, I finally decided to start converting this thing, I've ordered the 3-axis Hobby CNC Controller, and 3x 277 oz-in steppers. It'll be driven with EMC2 used it in the past with my own stepper controller so I know how to set it up. I should start getting parts later this week.

So, the first thing I've done is clean and fully tune the mill to the best of my abilities so far. I've torn the entire mill down and cleaned all the ways and regressed them as well as partially lapped the steel gib strips against a surface plate. Didn't do much to them, just smoothed them up a bit. After re-assembling the mill I went ahead and measured its backlash. I did not measure the Z-axis since I'll probably have to do some more work on it later, I'm not sure if 277 oz-in motors will be able to drive the z very well so I may need to get a gas-spring or build a counter weight.

Anyways the backlash on the x-axis is about 0.004", and the y-axis is about 0.005". This is on the stock screws, I do not really plan on replacing the stock screws as that seems to be more trouble then its really worth for such a small machine. 5 Thou doesn't seem too bad for the stock screws at all really, and I'm quite happy with it so far (but less backlash is always a good thing).

Going to try to keep a bill of materials running along so far (everything in USD):
HobbyCNC Driver: $79
3x Nema 23 277 oz-in Motors: $27.50 a piece ($82.50)
24v, 6.5A Power Supply: $24.95
6' Parallel Cable: $3.95

Total so far (excluding shipping): $190.40

On the 'To Do List':
Shaft Couplers (Probably spider/lovejoy type couplers)
Aluminum Stock (To build the motor mounts)
Misc Hardware (Nuts & Bolts to shove everything together)

[DeusExMachina]

First update:
HobbyCNC, Steppers, and Power Supply have arrived.

HobbyCNC went together without incident and is rather easy to put together. I'd recommend it to anyone with basic solder skills (or those willing to read some "how to solder" guides online) and a little understanding of some basic components. That said the instructions were simple, accurate, and easy to follow, and the number of components are as such that it is easy to sort and put together. Just make sure to pick up a cheap multimeter (they're really useful anyways...)

With everything sitting out and wired up to the desktop machine that'll become the controller, I can happily spin the steppers up to 60 in/min, which translates to 1200 rpm. Whether or not they'll have any usable torque at this speed I don't know yet.

Went ahead and order some lovejoy style shaft couplers, as well as a lot of aluminum to start building the mounts.

Keeping up with my expense log:
Aluminum Stock: $26.37
Shaft Couplers: $14.91

In hindsight it appears that the 24v 6.5a power supply I ordered isn't really enough. In the future once everything is all setup I'll probably order a KL-320-36 36V/8.8A Power Supply ($59.95) Has anyone delt with Keling Inc before? Their website isn't put together all that well, I've seen them mentioned a few times but I'm little leery of ordering from a site where they don't know what a <title></title> tag is for

Will be more updates this weekend, going to start ironing out all the electronics and get a good control box built. So far I've got EMC2 installed, and the HobbyCNC board setup correctly in it, so I really just need to sit down and build a box to shove everything in and work out the limit/home switches.

[LUCKY13]

Didn't read your whole thread, except for asking about Keiling.



Many here order from them alot. I would think there would be no worries buying from Keiling, in fact them and HomeShopCNC are the two prefered that most people buy from for this type parts.


Jess

[Crevice Reamer]

Keling products are a very good mix of quality and value. He usually ships the same day as the order is placed, and Priority mail will get it to you fast. The only problem is that if he is out of stock of what you order he may substitute something else without asking. His subs are not always the best match. Make sure you call or email for availability first, and specify NO substitutions.

Lovejoy type couplers are prone to backlash. Helical are MUCH better.

CR.

[gfc62]

Yep, no worries ordering from Keling. I've bought several things from him in the past. The only delay was when he told me an item was out of stock and I ordered it anyway.

[LUCKY13]

ALso yo ucan find many good parts for your machine at



http://http://www.littlemachineshop....e Machine SHop



The Belt drive upgrade for the X1 really is nice and helps these machines a lot. (BTW, Micro Mill = X1).


The backlash can be worked out to be better than you have. Many times the bearing blocks/end bearings will be the problem with the backlash on these mills with the kit your using. I think you can work with taking the slack out of the end bearing and get down to much tight backlash.




I will be building one of these mills soon myself. I only need a few more parts and a camera so I can document the proccess. When I do I will try and show how to get the slack out of these screws for the X1. I have mine down to very, very little right now (less than 0.001) and I have done nothing spiecial and I hope I might be able to get it a little bit better after I work on the gibs and dovetail slides.


Jess

[sansbury]

What makes you think the PSU is undersized--is this based on paper or is there an operational issue? I ask because I am running an X2 with 425oz motors with the same size PSU and it seems fine.

Jaw couplings definitely have backlash but for the $20/axis savings I can live with it. Based on visual examination I can't imagine them adding more than .001" on my X1. If you're careful with alignment you can always just use solid couplings, too.

[DeusExMachina]

What makes you think the PSU is undersized--is this based on paper or is there an operational issue? I ask because I am running an X2 with 425oz motors with the same size PSU and it seems fine.

Based on paper, I'm not going to mess with the psu until its up and running, if there's not enough power to keep everything moving at a decent rate I'll consider upgrading to a slightly larger one.

As for the backlash with lovejoy vs helical, I knew that was going to be an issue from the beginning, but for the time being I'm not terribly concerned about it. $14 for all 3 axis, or $60 for the helical couplers? It was an easy decision at the time, even if it is technically false economy I can still learn from a backlash ridden machine.

Clever programming can eliminate some issues with backlash anyways, so as long as I'm cutting straight lines for the time being I should b ok :P

Picked up 100' of cable, a 14"x14"x4" metal enclosure, and 10' of cable organizing tubing.

Enclosure: $35.99
5' Tubing (x2): $4.95 ($9.90)
100' Cable: $9.95

Running Total Thus Far: $287.52

Still need a nice big on/off toggle switch, fuse holder, some fuses etc, not really much left though. Just need to shove everything together.

[Crevice Reamer]

Sounds good so far. What about home or limit switches?

CR.

[DeusExMachina]

Actually plan on working on limit/home switches tomorrow. I bought a 15" touchscreen a few years ago, never really used it much, but did a bit of looking around and stumbled on a driver for the panel for linux Already got it up in running, so now I've got a touch screen to go with the machine

[Crevice Reamer]

KOOL!

CR.

[DeusExMachina]

Small hickup... I'm not sure if OpenCAM did it or what, but shortly after attempting to install it my libstdc++.so.6 got..well trashed, destroyed... This is rather important as it seems its a very basic library for c support, the system monitor would not even open with the trashed library. So after almost 4 hours of messing around trying to get everything working again I trashed the partition and I'm current re-installing.

Tried everything from rebuilding the links to the library to wiping it out and replacing it, etc etc, I really don't know what happened... But, oh well, should be back and running in about 20 minutes as long as I don't run in to another issue configuring my monitor again...ugh.

In other news, all of my electronics were running beautifully before linux nose dived. I've got to reset all my settings now but it shouldn't take too long.

[DeusExMachina]

Last night I got my couplers and decided it was time to try and shove everything together. I made a really simple motor mount out of 3 piece of 3/8" aluminum plate, unfortunately the mount is no where near rigid (nor even that well built) enough to work well. I only tested the x-axis, but I ran in to quite a few problems.

Going X- (...right...) I could move the table at about 35 ipm without losing any steps, but as soon as I flipped direction it'd start binding. I noticed that the lead screw was moving in and out of the handle mount (Think I found te backlash issue Lucky13 was talking about). I shoved an 8mm skate bearing inline with the coupler and got it to move consistently at about 6 ipm for awhile, once it gets closer to the leadscrew nut it starts to bind again. This is probably due to the flex with the motor mount, as it gets closer things start to tighten up and there isn't enough room for the motor/mount to continue flexing....

So, it looks like for the time being I have a really inconsitent autofeed

I ordered some thrust bearings last night, hopefuly those will help get a little more consistence/speed. If I can get it to even run slowly (without losing steps) I can use it make some better bearing blocks and motor mounts.

[DeusExMachina]

Well my first experience thus far with my 2-axis cnc'd x1 have been, mixed. Quite awesome watching the table move around cutting things faster, more accurately, and with a far better surface finish then anything I could have done manually.

That said, my first parts appear to be a write off for the most part. I tried to produce a much better bearing block and motor mount then my temporary and horribly produced ones that I currently have (quickly, and not even quite straightly cut on a bandsaw heh). My design I believe is sound (for the most part, couple things should change) and my NC files all behaved nicely with EMC2 and ran just fine.

But, my parts are non functionally inaccurate, the shafts for the lead screw and stepper mount are off by as much as ~0.03" and I think the hole the lead screw passes through may be at a slightly angle. Even with lovejoy style couplers this is too much, there is consistent binding every turn, for a bit I had hoped that the leadscrew/coupler would settle if I let it run for awhile, but an hour later (at a measily 120rpm which is all I could manage without the motor stalling) it still hadn't gotten any better...

Most of I think stems from lack of experience with setup and fixturing, and a basic lack of tooling... I don't have a parallel set, I don't have a clamp set, my vice is a 4" drill press vice (which try as I might, the part always raises up when clamping, and the stupid thing is really hard to tram). I don't have a surface plate, nor any 1-2-3 blocks.

I have a set of digital calipers, and a dial indicator, thats about it for my setup equipment...

Add lack of equipment to lack of experience and you end up with just a lack...
Heh, for instance, to locate the edge for my motor mount, the first thing that popped in to my mind is I'd just use my cutting tool and center one corner of the work piece under and home my axis... Why oh why I didn't think to put my drill chuck and and put something of a known diameter in it I have no idea. Could have just walked to work piece up to my probe, then added the the radius and homed the axis, poof done, accurate. Ugh, learn as you go...

Think I'm going to treat my self and order some half decent equipment that I should have a while ago and then try again.

Hey look a picture!? Here's the mount I was trying to build, if anyone is interested I can post some more details.

[sansbury]

You'll be able to do better than .03" even with a pretty badly knocked-together X1 conversion. A half-decent vise is a good place to start

Aside from that something worth thinking about is how to design parts so that they require less precision to begin with. Don't make a hole a tight fit if a loose fit will do.

Another thing is to try and avoid parts that push the weaknesses of the machine too much. I could see a part that has a lot of Z-depth like this (appears to) cause some trouble. If you look at my X1 below, you can see that the motor mounts are multi-piece and this eliminated the need to drill/bore anything deeper than .500".

Beyond this I'd want to know more specifics about how you actually milled the part in order to get a sense of what might have caused problems.

[DeusExMachina]

You'll be able to do better than .03" even with a pretty badly knocked-together X1 conversion. A half-decent vise is a good place to start

Aside from that something worth thinking about is how to design parts so that they require less precision to begin with. Don't make a hole a tight fit if a loose fit will do.

Another thing is to try and avoid parts that push the weaknesses of the machine too much. I could see a part that has a lot of Z-depth like this (appears to) cause some trouble. If you look at my X1 below, you can see that the motor mounts are multi-piece and this eliminated the need to drill/bore anything deeper than .500".

Beyond this I'd want to know more specifics about how you actually milled the part in order to get a sense of what might have caused problems.

Well I believe most of my problems stemmed just from poor setup. Though yeah you're right, milling out the pocket for the coupler took a very long time, and ended up causing most of the problems. I milled about ~0.5" then had to flip it over so I wouldn't hit the vice...It looks like I was off by about 0.01" when I flipped it so that screwed quite a few things up. On top of that I didn't have the machine well homed, looks like the majority of the innacuracy was here, was off by about 0.1" x, and 0.05" y, backlash etc kind of compounded and I ended up with something that looked nice until I tried to bolt it together

I made the mount in 5 operations. Technically operation 0 being cutting and facing a chunk of 0.75"x3" al plate. I cut my plate to about 2.45" and then faced the two bandsawed ends so that they were square. Leaving just about 2.3" of stock or, I then faced off one end until I was down to 2.25 (think it came out to 2.3 something and I decided that was close enough as the length didn't matter so much.

The first operation was milling out the center pocket.. I clamped my blank in to my vice with ~0.6" exposed above the vice. I don't have the z actually cnc'd yet so my code has pauses to allow me to feed the z. Took 48 passes total at about 0.015"/pass (all milling ops were done with a 0.25" 4 flute [I know I know, 2 flute for al but I dont think the stupid spindle turns fast enough]). Some where just past half I needed to flip the blank over to finish the pocket (which is a major hickup point it looks like).

Second operation is to mill out the two channels so that the cap screw that attaches the bearing block to the table has clearance (I've sense learned that his needs to be a tiny bit deeper...) Again 0.25" end mill, 0.015" DOC, about 10 passes were made.

Thrid operation is to mill the stepper front plate clearance pocket (or whatever you want to call it). Turn the vice end up, again 0.25" EM, 0.015" DOC, ~15 passes.

4th and 5th step were drilling ops for the the 4 #10 machine screws used to attach the mount to the bearing block, and the motor to the mount, as well as a 5/8" hole in the top to allow the stepper shaft through.

Then I had to tap the four screws ...

Most of the issues seem to stem from poor edge finding and stupid screwups :P I may be able to save the part if I band saw it in half so that I can properly line up the stepper shaft and leadscrew shaft. I may try that soonish.

Though I think I'm going to go back to the drawing board and make it more simple. If you don't mind, do you have any better images of your mounts?

[SCzEngrgGroup]

First, you should invest $10 in an edge/center finder:

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

You'll find, as you get more experience, finguring out the setup, properly locating the work, and clamping are the biggest issues. The design and G-code generation are often trivial in comparison. You must think long and hard about how many setups you'll need, and how to hold and locate the part for each setup. It does get easier with practice (eventually....). If you're going to have to move or turn over the part mid-stream, you want to make sure you have one, or at most a very few, accurate fixed reference you can use for all the setups, to minimize errors. I usually use a combination of machined edges, and/or holes, all of which are machined in a single setup so they are as accurate as possible. If you do this, achieving at least 0.010" accuracy on all dimensions should be almost a no-brainer.

Regards,
Ray L.

[DeusExMachina]

Thought I'd post this, its the first two parts I've made with my machine, they are the ones that can't really be used since they don't line up correctly. That said I'm still kind of proud of them

[sansbury]

There is a Yahoo group dedicated to this mill, I believe I found the drawings there:

http://groups.yahoo.com/group/hf47158toCNC_Moderated/

Do those blocks have anywhere to mount bearings? You can use ordinary skate bearings (608ZZ type) which are dirt cheap but they make a huge difference in manual operation and are more or less essential for CNC.

[DeusExMachina]

Been doing mostly designing the last little bit, holidays and all -- family kind of frowns on the mill running and me missing

I've tried to come up with something extremely simple, and while the below doesn't really look it, it should be far easier to build then my last complicated design. On top of that, there's room for adjusting basically everything to get the shafts lined up.

I am a little worried about how stiff this arrangement will be.

Its similar to most of the mounts I've seen all over the net, but seems to have more parts. I've seem threaded drill rod (that was threaded on a lathe), I've seen large plastic (delrin?) that's been drilled out with really, really, really long bolts I've also seen extremely long thread couplers... But since I don't have a lathe, nor do I know where to find extremely long thread couplers, I'm kind of stuck with I can find locally (since I'm getting extremely tired of shipping charges). So, hopefully this'll be strong enough.