My third build, all steel this time!

[kimosawboy]

When you did your deflection test ..did you use mechanical means to hold the gantry in place???
G Vavra

[LazyMan]

After having these rails and playing around with a 20mm SBR that a friend had, I am sure I made the right choice even though they cost a little over twice the price. Hell, they would have been worth it a four times the price.

Absolutely. I think there are quite a lot of people who don't know how much more rigid and accurate a decent quality profile rail is over SBR Chinese rails. Anyone putting a lot of work into a machine would be doing themselves a disservice to use SBR rails. I built 2 machines with SBR20 rails. Yes the machine could still produce decent work but, I finally "saw the light" and tried some profile rails. No comparison.

[steve123]

I'd just epoxy in some plywood plates to stiffen up the tube. Before you do that, cut a snug fitting piece and press it into the end and redo your deflection test. But I would think it would be fine.
.

I was thinking something like that. Put in some partitions (starting in the center). Put a few bolts sticking into the void in an inch above the partition from the sides/top/bottom. These will help stabilize the plug you are about to pour. Then pour in a few inches of something like epoxy-granite or non-shrinking concrete. That would give you two things: Stiffness and Damping. I would think that 3 of those (1 center, and 2 ends) would be enough.

My gantry is made up of two 3 x 5 x 3/8" tubes. I plan to fill them completely with concrete.

[bob83]

Did you decide on the servos from automation technologies? I have been banging my head against the wall trying to decide what I think about those servos. Not very many opinions on them.

[Fluxion]

I haven't decided what servos or steppers I will be using. I have emailed several vendors about their steppers or servos and of course they all say theirs is perfect for my application. I am at a loss as to what to do now. I am slowly getting other things done on the router though, I'll get some new pics up here tomorrow.

[widgitmaster]

This is a quote from CNC Router Parts.com

This was the most informative page, and helped me choose for my Big RED Monster build!


Why should I buy your motors? Company XX has higher torque motor
We get this question a lot: "Company XXX sells motors with a super high stall torque (oz-in) rating -- won't I get better performance from these higher torque motors"? The answer may surprise you!
Unfortunately, the main statistic advertised on stepper motors is probably the least useful of all -- stall (or holding) torque, which is the torque the motor puts out when it is not moving. This isn't terribly helpful, as your motor isn't doing any work when it's standing still! All steppers run at less than their stall torque, so what's far more important is the usable torque of the motor throughout its RPM range. The "flatter" this torque curve, the more usable force (for accelerating and decelerating) you'll get out of your drive system.

All stepper motors also put out less torque the faster they rotate. There are two key values that you should be looking for in a motor that influence its performance: current and inductance. First of all, you should look for a motor with a current rating that is less than or equal to the current rating of your motor driver. Motor torque scales linearly with current, so if you are (for example) driving a 5A motor at 3.5A (the maximum the G540 drive can put out), you are only getting 70% of the motor's rated torque. All other things being equal, a 425 oz-in, 5A motor running at 3.5A will actually achieve less torque than our 320 oz-in motors running at 3.5A.

The other important thing to look for is the motor inductance. The lower the inductance, the slower the motor builds up "back EMF voltage", which reduces the torque of the motor. While higher inductance can be overcome with higher voltage power supplies, this adds extra heat and expense to a system.

We invite you to look at competitor offerings, and see for yourself why our motors are better. We offer motors that are matched to the current ratings of the drivers we sell (3.5A / phase in our Nema 23 products for use with Gecko's G540, and 7A / phase for our Nema 34 products for use with Gecko's 201x and 203v products). Our motors are also low inductance, 2 mH for our 960 oz-in motors and 2.8 mH for our 320 oz-in motors, both of which work great with commonly available 48V supplies.

So don't fall for the hype -- wiith our motors, we've had customers gain 3x speed increases over motors with higher rated stall torques. We've tested our motors and competitor motors with our mechanical systems to find the best value for you. Buy from a name you can trust to get the most out of your machine.

[awerby]

Nice build! I've been thinking along similar lines for the next machine I'm going to make. If you want to beef up those tubes, why not just insert some round-cornered square plugs in there? You should be able to slide them into place and inject some epoxy to fill any gaps through some holes you drill, and then put screws in the holes to keep the plugs in place. I'd go with servos too - the Gecko G320 drives are pretty easy to configure; they'll work the same as steppers given step-direction signals like Mach3 or LinuxCNC puts out. Servos have plenty of speed, which doesn't compromise their torque, so you usually need to provide some kind of timing-belt pulley reduction.

[Fluxion]

I have been in contact with Cory at cncrouterparts.com and he assures me that their nema34 steppers with either the Gecko 201x drives or their new Leadshine manufactured CRP8070 stepper drives would be a great match for my CNC router. I have also exchanged emails with John at automationtechnologies.com and he thinks that his 1150 oz-in DC servo kit would be "ok" with my already purchased 3.2:1 belt reduction. I am still concerned that the reduction won't be enough for servos, I am still trying to decide on this. I have also been looking into Dmm-Tech.com AC servo kits but these are a little more money.

Even though I can't make a decision on what motors to go with I have made some progress.

I removed the gantry so I could add some rebar reinforcement inside the gantry tube. I used West Systems 105 epoxy, 206 hardener and 404 high density filler to glue them in place. I glued a few test pieces inside a scrap of 4x8 tubing and after 2 weeks I am shocked at what it took to knock one out with a hammer! This is some seriously strong epoxy.



While the gantry was off I used this opportunity to drill and tap some new holes in the drill press for mounting the belt drives.



I have also started on fabricating the Z-axis from Mic6 plate.




I got the Y-axis belt drive and rack screwed in place. I was able to get the rack to within 0.003" parallel to the linear rails. I hope this is close enough.





Here is a pic of the Z-axis router plate mounted, you can see a mistake here and it does bother me but I don't have enough Mic6 to make a new one.


Here are a couple more pics as it sits as of now.





I'm home sick from work today but I am feeling much better so I think I will go out to the shop and start mounting the X-axis gear racks.

Now for the big question, what color should I paint this thing? The frame was painted with Rustoleum hammer tone silver but I'm not digging it, it's half primer now after all the changes I've made. My other two routers were blue and I had considered red but I think this might be too big to go red or blue. I have gotten used to the white with green stripes router at work but that's kind of boring.

[pippin88]

I'm interested in what difference your reo bracing within the gantry makes.

I've used a similar gantry and it would be easy to add in to mine.

[LeeWay]

Looking fantastic.
As for color, it is purely your choice. Do you have a favorite college or pro team? That color scheme may work. Also in the 50's, they had lots of cars come out in some really nice two tone color combo's. You may find one of those you like.I don't think you can make a bad choice in color though with such a machine. Purple sparkle and chartreuse would probably be just fine.

[alan_3301]

Nice machine!

I would stay away from servos if you are stuck with that gear ratio.
Unless you want a rapid speed of almost 3000ipm, then you will never see the power they are rated for.
You would need another 2.5:1 reduction to get the most out of those servos. (Assuming 3000rpm max rpm)
That will give you 1178 ipm rapid speed, 2.5 times the torque at all speeds, versus the gearing you have now.

If that isn't easily done I would stick with steppers.

[greggv]

You might also want to look at Automation DIrect. They sell servo and steppers and their drives, cables, etc at very reasonable prices and have great support.

[jefersonbmx]

Amazing machine Fluxion.

I'm sorry if I missed this in post. But how was made the base to Y rails (epoxy too?), and how you got this perpendicular to the bed / bottom of base of the gantry that was epoxy pouring.

[ClaudDKLyons]

You might also want to look at Automation DIrect. They sell servo and steppers and their drives, cables, etc at very reasonable prices and have great support.

[wsnake]

bump : how's this build going?

[Fluxion]

I have been absent for quite a while and have not updated this thread, for that I am sorry. The good news you guys didn't miss anything. Work has been crazy busy, we build cabinets and counter tops for military barracks mostly and this is the busy season. My wife is sick with a few chronic problems that has had her out of commission for some time. Life got in the way I guess. I am back on the project now though, I have purchased the Nema34 steppers and Gecko 201x drivers from CNCrouterparts.com. I still need a power supply, Breakout board, ESS, spindle, VFD and a computer to run it all. I have done a few small things however, I will post some update pics later tonight. I have 3 older computers here at home all in compact cases running windows XP pro but none of them will boot up, they worked a year ago, into the trash they went. I'll be building a new computer just for this router. I will be using windows 7 for sure and I would like to use a micro atx sized board. Any suggestions on motherboard / processor combinations?

I am now debating buying the 48v power supply from CNCrouterparts or getting a toroidal power supply with a higher voltage like I originally planned. I know the 48v is better matched to the steppers and going to something like a 72v will cause some more heat in the steppers bit is will give more power. The big question is will it be worth it? Toroidal power supplies are a bit cheaper than the switching supply CNCrouterparts sells too.

Now to answer a couple questions:

I'm interested in what difference your reo bracing within the gantry makes.

I've used a similar gantry and it would be easy to add in to mine.

The re-bar made a HUGE difference! I can no longer measure any deflection by pushing on the gantry tube with my hands and I am down to a very small amount of movement on the z-axis with the carriage at its lowest point. I am very happy with the addition even though I did add another 10 lbs or so.

Amazing machine Fluxion.

I'm sorry if I missed this in post. But how was made the base to Y rails (epoxy too?), and how you got this perpendicular to the bed / bottom of base of the gantry that was epoxy pouring.

Yes, the base for the Y axis rails were poured in the same epoxy. The forms also allowed me to fill the rounded corners of the gantry tube at the same time. The rails themselves are placed on the rail bed in a location that allowed me to put the mounting holes in the flat part of the steel tube, right before the radius corner starts. To get the Y axis rail beds perpendicular to the base of the gantry ends I had to make two separate pours. The first pour I made with the gantry upside down and leveled the best I could get with my Starrett 98-12 and 98-6 levels. I used my 6' level that has milled sides to lay across the feet with the Starrett 12" level on top in order to level the gantry assembly along its length. This pour was to level the feet or base of the gantry ends to ensure they were both in the same plane. I had to construct a bridge between the two feet to allow the epoxy to self level. The pics of this are in my first post of this thread. To pour the Y-axis rail beds I had to lay the gantry assembly on its back then get it leveled along its length. In order to make the rail beds perpendicular to the gantry feet I clamped a precision machinist square to the poured surface of the gantry feet and used my Starrett 4" level on the horizontal beam of the square. I wish I had taken a pic of this setup but I never did. I hope that makes sense.

[Fluxion]

I had internet problems last night and uploading photos took forever. Here are some new pics!



These first 3 pics show the covered cable trays I built to connect the control cabinet to the E-chain on the X-axis. I still have a bit to do to hold the cables on the gantry.









This pic shows the start of mounting the Z-axis E-chain. Its going slow but I am making progress at least.





This one shows the Z-axis motor mounted and the coupler here is actually solid aluminum bored to couple the 1/2" motor shaft to the 12mm ballscrew end, it is also the same length as the Oldham zero backlash coupler I have purchased. This solid coupler is only for mock up and alignment purpose. I do have the Oldham coupler that I purchased from cncrp (along with everything else). I had to buy one side at 10mm since they didn't offer 12mm and bore it on the lathe to 12mm but that was cake.




Not to much new here just the back side of the Z-axis showing the Y-axis motor mounted. You can also see the Oldham coupler sitting on the gantry tube. I need to fab up a bracket of sorts to attach the two E-chains to the Y carriage.





This pic shows one of the X-axis steppers mounted up. You can also see where the 4 pin XLR that came on the motor lead will plug into the foot of the gantry.





I should be getting a sheet of 3/4" phenolic to make the mill table soon. It is leftover from a job at work, we are waiting on the job to be paid so that we know we won't need to remake anything out of this sheet. The table will be made of two layers and I am planning on using the lower layer for a vacuum plenum by routing a dispersion grid pattern. The upper sheet will form the table surface and will be routed to match the NEMI grid we have on our Onsrud at work. I will probably use a MDF spoilboard most of the time.

I need to order the ESS, power supply and a breakout board. Any suggestions on the breakout board?

[Fluxion]

Ok, I pulled the trigger on the PMDX-126 and PMDX-107. I know there are cheaper breakout boards with the speed control built in like the CNC4PC c-11. I have done quite a bit of reading about both and really haven't read any problems with the PMDX and all the comparisons I could find said the PMDX was built better and quite a few have replaced the c-11 with the PMDX-126.

Now that is out of the way, the ESS is coming next, along with a tank of argon for my new tig welder.

[wsnake]

Still following this thread with heaps of interest and a bit of envy.

Unfortunately your past the point of where I could offer any insight. Keep up the great work!

[Fluxion]

Wsnake, I'm glad someone is watching! Actually I do keep an eye on the number of reads this thread gets so I know people are looking. I and going to try and post more, this is a great community but the interaction seems to have slowed down recently.