80/20 mill build

[digits]

Have you tried working out what sort of cutting forces you are expecting? I found some good formulas on the web, and worked out that cutting with a 6mm endmill, 2.5mm deep in Aluminium at 600mm/min, I would have a force of about 200N on the cutter. I then just sized everything to take way more than twice this force

On a 10mm pitch screw, you have a mechanical advantage of about 600:1, so your 470ozin / 3.3Nm motors will be able to resist a backdriving force of about 1900N - equivalent to lifting 190kg/400lb with 1:1 gearing.

[LeeWay]

Thanks Digits.
I'm not an engineer nor mathematician nor electrical guru for that matter. I have trouble working out formulas and while I can do it sometimes, it makes for a lot of head scratching and research. I majored in.........uh........art. I know. Dumba$$! The numbers you crunched sound good to me.
I tend to over build everything because of this. Over building generally costs a little more, but in the case of my router, it does more than expected. I think hobby CNC machines like woodworking lends itself well to over building. Now aviation and transportation are two areas where over building can be bad. Formulas, tolerance and exacting specs are a must for those type things as they are in commercial machining.
This mill here isn't exactly being over built by using aluminum, but I am using something I can both afford and work with to hopefully achieve the desired result and have the satisfaction of doing it myself....with help from you guys, of course. Thanks again for the numbers. I would have wound up doodling Whistler's Mother before I worked out those calcs.

[digits]

I think 80/20 has rather a bad rap - but I defy anyone to say that The Swede's beautiful machine on 5bears.com is flimsy I also just bought an bandsaw with a cast aluminium base- it's solid enough, but only 25kg which is a real bonus for me.

I really can't see myself ever wanting to carve a 2" wide swathe 1/2" deep in steel in a single pass on a hobby machine in my spare bedroom, so I really don't think I need 300kg of cast iron on my desk! I did however think that it would be a good idea to do some calculations to determine whether my intended speeds and cut depths were feasible on an 80/20 machine.

What are you planning to cut on your new machine? I am more interested in 3D than 2.5D myself, so I've come to the conclusion that speed really does matter on a small machine. I need to take thousands of very light cuts, so 30IPM rapids really won't cut it - I have that already and some small jobs that would require 40 hours of cutting!

I look forward to seeing how your machine performs - if you're using belt drive, you have the wonderful freedom to optimise it for power/speed after it's all together You can also adjust or even reconfigure your framework after it's all together - I'd love to see someone do that with welded steel

[LeeWay]

I think your right about it's versatility. 80/20 is some cool stuff. The thickness on all this particular extrusion is over 1/8" thick.
These 2' extrusions weigh almost 14 pounds. 13.8 for 2 foot. 14.6 for the longer one.

I did some weighing so far and here are some initial poundage.

2' extrusion............................13.8
2' 1.5" extrusion......................14.6
4" by 5" by 6" angle plate..........8
x axis long screw.....................3.9
y axis short screw...................3.8
x axis ways............................15.4
y axis ways............................13
z axis....................................30.6
cement dry in cans..................23.2

total so far.............................126.3 pounds or 57.28 kg

Doesn't include rebar, threaded rods, lead shots, assorted plates and mounts, mill head and spindle motor, bolts, steppers and covers yet either. Some of that should add quite a bit to the weight. I am probably looking at well over 200 pounds when complete. Then it's going to get enclosed and have coolant. I haven't decided between flood or mist yet, but leaning toward flood. It seems like it might do a better job.

Right now I mill small brackets out of mild steel and aluminum for some models of table saw blade guards that I produce. I want to do those on the machine as well as increase my lineup of brackets available to other saws. Right now I only make them for saws that must have something due to the design, but its a nice feature and would work well on other models. I cannot produce enough by hand to make it cost effective to make that jump right now. After that, who knows what I will wind up making with a nice little mill.
I should get over 8" travel on the y, over 16" on the x and have 9" but expandable by three or 4 inches on the z.
That should work nicely. My X2 has let me down a few times already by being so small.
One day maybe I'll find a Bridgeport. Thanks again.

[Deviant]

Any progess pictures on this?

I was actually looking at using 80/20 stuff to build a lathe.

I think my current mill will perform the majority of my work, however I can think of a few items that I would like to have a long x-axis. I was considering using the 80/20 for a bridge style setup. Should be able to make it very rigid and consistant under the bridge.

[LeeWay]

Nothing further yet. I think it might work well in your app. I do know that I am nott going to rely on the T-slots of just one side, but rather three sides for my Z axis. It would put a lot of weight and pressure on just the front slots. I will make up at least a u-shaped channel to attach the slide to. I may even make it wrap all the way around. I haven't worked that out yet.
This one will take some time for me. I just don't have a lot of it right now. Possibly will have more to show next week. Thanks.

[LeeWay]

..............

[LeeWay]

I have tinkered a little more with this, but no pics yet. I have a question.
I intend to use another mini mill spindle head for R8 so I can use the tooliing I already own. I will buy another to keep my manual mill working.
I will be using a larger motor with a belt drive and may at some point build a power drawbar.
My question is B-7 grade threaded rod 7/16"-20 good enough to use for this? I would think I need a little more room for the drawbar after pulleys and motor mounts go on. I was considering using a taller bushing and a longer threaded rod to give me more height and then design possibilities later. I know my little manual mill could benefit from a bushing to keep the drawbar centered as well, but any info or experience here will be appreciated before I order.
Thanks.

[LeeWay]

I found the answer to my question I think. That grade should be fine for a drawbar. It's gotta be a step up from the OEM bar on the X-2. I finally ordered the R-8 mill head. They came in at Little Machine Shop. I will shoot some more photo's when I have made enough progress to justify it.

[LeeWay]

Here are several more photo's of a little progress.





















The images are pretty self explanatory. The thin plate I used on the rear angle plate was just to get the shape so I could more easily mill the correct fitting shape in 1/4" plate. I didn't have a way to mill down in between the webs to get the angle plate flat. This pate serves as both a washer and a cover plate to keep stuff out of the angle plates slots.
There will be a rod in every hole you see in the extrusions. A little overkill is fine on cheap parts like that.
I have reconsidered about trying to tension the filling in this with the larger rods. My initial idea proved not to be very easy to do right. It was a matter of the slot placement. I would have had to put the tension rod in one side of the fill. Still considering options. Its not too late until I actually fill the tubes.

[LeeWay]

The slots in the 80/20 are very nice for setting up and building the machines structure, especially when test fitting things and making modifications.
They will almost totally be covered up on this build when I am done. You won't be able to see any of the slots except maybe at the back of the column.
This leads me to an issue that I think may come into play. Pooling of coolant in the slots.
I plan to use flood coolant of this. I don't think a little coolant will be bad, but pools of it sitting in the slots and not having a way to drain are not desirable. I know that have some slot cover material, but I think I could cover the exposed sots under the ball screw with aluminum instead. This would keep most stray swarf out. I guess the easiest solution will be to put 4 weep holes in each end of the front to back running slots. Bored through all the plates. I could then periodically use some compressed air to blow out any coolant that seeped down in these 4 slots.
The plate on the front of this Y axis is left a little tall right now. It will get another plate added to this to mount the motor on. Then I will determine where it needs cutting. I will hook up the motors direct drive initially, but with this plate design, it will be easy to switch to belt drive should I need to down the road. The Y axis will have a rigid motor cover. I thought about using a rigid way cover too, but that would extend out too far forward I think. Way covers are a must on the Y. The X and Z will be relatively easy with something other than the acordian style, but it looks like the acordian style will be the best solution for the Y.
The sides will have gussets and plates. Then each side will get 3" by 3" steel angle running the length for mounting and to spread the footprint.
I did receive the R-8 mill head from LMS. I will have to gut it out.

I have a question on the Z axis. I want to take the load off the motor for controlling the Z. I have several different hydraulic shock spring thingies with different strengths.
I have thought about using the air method where you balance out the mill head using air in a small tank and an air cylinder. This sounds lile a nice way to go. My Z will have a 9" stroke. Anyone seen any air cylinders with this length stroke suitable for this? Anyone seen any threads here discussing something like this? I also considered door closers. I have a few of these in different sizes too, but they are not ideal. At least not as far as linkages go.
Thanks for looking. I'll post more when I can.

[LeeWay]

I was finally able to get some more done on this project. It is incredible how little time you have when you have many many irons in the fire.
I guess it's worth it, because the time I do take to work on these machines is very satisfying.
I am working on a plasma cutter as well, so time gets kinda split between the two.
I am actually using some of the parts I bought for the plasma on this machine and my router. I used the entire control system and motors destined for the plasma on the router. Nice Gecko 201 setup. That really made my router preform as I never expected. I am using the Xylotex system from my router on this mill.
I bought new 203V's for the plasma when I get back to it.

I decided to use chain drive on the Y for the time being. I had it on hand. It seems to not skip a beat so far. Nice and tight setup. I will likely drive the X and Z the same way at least temporarily.
Then the machine can mill new parts for a nicer drive setup once it's going. Probably wind up with belt drive for more accuracy.

The way my rails are, I was able to use the same outer holes in both the X and Y blocks. This made alignment that much easier. I used a clear quilter's square to align the X to the column. It has lots of little perfectly square lines and it made it rather simple to align. I know this is the squarest thing I have in the shop. I use it to align my sliding miter table on my saw and get perfect results from it. A dial indicator made the rest of the alignment a breeze. I will use an aluminum plate with another T-slot plate mounted on top of that and then flycut on it's own. I will mostly be using the 5" vise in the pics and plan on getting a mag base as well. These and the T-slots should give me all the mounting I need.
Anyone use coolant on a mag base? Think it will effect anything? Curious. It doesn't seem like it would, but that is one of those things you don't want to learn the hard way. Anyway, pics are pretty self explanatory.
Feels good to get a little done on it.

[LeeWay]

More pics.

[WilliamD]

Looking real nice! That should be one silky smooth setup when you're done. Do you buy chance have a personal comparison between rolled ballscrews and the ground one's you're using. Ground as so much harder to find, but I've yet to see someone say they are definetly worth it. Just wondering if you have any experience on the issue. Congrats again!

[LeeWay]

The rolled screws on my router is really all that I have given a good workout. They are pretty smooth and accurate themselves. The Y axis on this one is all I have powered yet. You are right about it being silky smooth. I ran it at 120 IPM. That is really too fast for this machine I think, but it should certainly be able to cut some parts out quickly.
The ground ball screws in this case was just a good find on Ebay. I think I was the only bidder and I got these two screws and the Z assembly for less than $200 shipped IIRC. These were sold as used, but appear to be and run like new.

I think the deal with ground screws in general is that the parts all fit together better and therefore are more accurate and rigid. Better fitting parts will also increase the life of the parts in a commercial app. I just don't see my machine wearing out the rolled screws at least no time soon. I can see no wear on them after a couple years use. Mine does semi commercial use. I run the router one day a week every week. Sometimes a little more.
I don't think the ground screws are ever worth it for a hobby app. That is unless you can get them the right size and length cheap like I did. I just lucked into them.

[LeeWay]

A few words about the saddle material. This is some "Extren" plate that I picked up from my plastic supplier. I wanted to see how well it would be suited for machine parts. I am pleased with it's rigidity and flatness. It drills and taps very well. It is a little hard on tooling however and if you don't like handling fiberglas, you won't like this stuff. It will itch you like crazy. It needs to be sealed once cut to control the little fibers. I have more and was intending to use this on the table and the column. I don't think I will though. The cost of this stuff would normally be on par with aluminum plate. At 1" thick, they both seem comparably rigid. Neither will rust. Both drill an tap nicely. I will see how well this stuff holds up now. It is in one of the highest stress points on this machine, so we'll see.

No problem if I need to remake it out of aluminum or steel though. I still have the clear polycarbonate template for the saddle.

[LeeWay]

Well I did manage to get this thing running. I got terribly tired of trying to manually mill out parts with my X-2. Way too small for one thing and I ain't good enough with a boring bar to get what I needed. X and Z are both direct drive. One of the first things this machine will cut out is a front mounting bracket to use the timing belt rather than the chain drive that is one there now. It seems to work well enough, but I also want to raise the motor up so it doesn't sit in the drain pan. That is coming soon as well as coolant. I picked up a 3.5 gallon parts washing bin from HF. It should work fine as a coolant tank. It already has a flex nozzle, so I should just need some tubing and then a drain in the pan.
Will install angle iron feet on the sides for mounting. I will raise the whole machine about 1/2" on pads.

I had to install a gas spring for the head. It would easily spin down when power was cut.
A single spring does okay, but if I put a little down pressure on it, then it slips too. I may install the second spring if it messes up.
Here is a link to those springs.
http://www.surpluscenter.com/item.as...name=hydraulic

I wound up with 14" travel in the X, 9.5" in the Y, and 9" Z.
That is monstrous in comparison to the X2. I think it will be fine for what I need.

I ordered a belt drive kit for this head and will use some of those parts to install the bigger motor that I have later on. I left the head mounting plate long on the left side to accommodate the new motor. I'll put the X2 back together and make it a dedicated drill press or something.

Still have to add my limit switches too. I have them all wired, just need to mount them. The 80/20 makes that fairly simple.

The head is trammed and the table tracks perfectly. I am pleased so far.

Oh yeah. Way covers too. I have some thick roofing rubber that should work good.

I'll post more when I have cut something.

[LeeWay]

I cut my first couple of parts out. One in aluminum with no coolant and the other is some standard cold rolled steel sheet. 12 gage or .105". I cut the aluminum using 1/8" 4 flute carbide mill. No real problems with this.

I cut the steel with 1/4" carbide mill and the is where I ran into trouble. I was cutting with coolant at 30 IPM and removing .014" material. I just installed a belt drive kit on the X2 head. That is nice. Taking this cut is steel kept stalling out the motor. I don't need to mention that no matter how fast you hit the Estop, you have lost steps when this happens. I could probably take lighter cuts or slow the feed, but the X2 motor is simple very underpowered for a machine this size.

I have the bigger treadmill motor and will need to install this next time I get to play with this. I also ordered a 48VDC, 7.5 A PS. The 28VDC I am using now is a little underpowered for the Gecko's.

I don't see any backlash, but I will put a dial on it and see what it is. It has to be very minimal. My parts came out decent.
I will use the pulleys off the belt drive on the new motor. Leave the base plate for it in place as well, but the mounting for the new motor will need to be vertical or a standard base rather than face mounted. I need to enlarge the hole in the small pulley to 5/8". Need a longer belt too.
I will get some more pics when I get some of this stuff changed out.

Comments are welcome as always. Thanks.

[acondit]

Lee,

What did you make the table out of?

Alan

[LeeWay]

Right now, the table is just 1/2" aluminum plate. I have a T-track plate on top of it. It is a 99 cent surplus find. It is normally used for mounting computer and radio equipment in vehicles. This is really just temporary as well. Most of my brackets will be cut in a milling vise anyway. This plate is plenty strong enough to hold a vise.
I want to buy a cast iron plate with T-slots milled in it. I know one guy here makes these and sells them on Ebay. I plan on contacting him for one. I didn't see any up there right now.
I didn't notice any flexing in the column. I still intend to install gussets on each side, but so far they aren't needed. I don't have that 2.5 HP motor installed yet though. That will put some torque behind the cutter. It should make any flex apparent then.
I add more later this week after some product ships. Then I think this machine will be working full time till Christmas.