MSC has 1/2-10 2 start and 5 start (5 tpi and 2 tpi - turns per inch), and also 1/2-8 2 start (4 tpi). Probably some other sizes, too.Originally Posted by Dylwad
http://www1.mscdirect.com/
Page 3856 at the bottom.
MSC has 1/2-10 2 start and 5 start (5 tpi and 2 tpi - turns per inch), and also 1/2-8 2 start (4 tpi). Probably some other sizes, too.Originally Posted by Dylwad
http://www1.mscdirect.com/
Page 3856 at the bottom.
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
having a lower turn-per inch on your lead screw kills the resolution of the system. If you're going to use Acme screws, look for 10 TPI 1 start or 20 TPI 2 start to get 10 turns per inch. Either way, the average 1.8 degrees per step motor will give you 2000 steps per inch, or 0.0005 inch resolution. Using a 10 TPI 5-start screws would give you 400 steps per inch, or 0.0025 inch resolution. Yes it would move faster, but it would also load the motors a lot more.
No one building a homemade wood router needs .0005 resolution. You'll be lucky to get .001 accuracy. Consider that .0025 is less than 1/12 of 1/32.Originally Posted by PaulH
6 Steps to make up 1/64. That is more than enough accuracy for 99% of the people here. You could always gear down a little bit to get closer to .001. Wood changes from humidity can be much more than that from 1 day to the next.
Also consider that decent quality acme screws are only accurate to plus or minus .009/ft. So in 2 feet of travel you could be off by as much as .018, and there's not much you can do about it.
Find the thread by Inventit about his router. He used 1/2-10 5 start with 400 oz motors, and I think got over 300ipm.
The 1/2-8 2 start or the 1/2-10 2 start are good starting points, as long as you have enough torque. They probably won't work well with the 150oz motors a lot of people here use, but they should work great with your 640 oz motors. I'd get the 1/2-8, as it's cheaper and you should have plenty of power for it.
One more thing is that multiple start acme screws can be up to 50% more efficient than single start screws. So if you have big enough motors, you'll waste a lot less torque spinning the screws. And higher lead screws will spin slower, so whipping will be less of a problem. I've read a few posts from people using 1/2-10 who's speed is limited by the screws whipping at higher rpm's. Don't underestimate the importance of speed. You WILL want to go faster.
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
The 1/2-8 2 start from MSC is $26 for 6 feet, not too bad. I could play with gearing on the motors if i find i need more resolution/torque, which is the nice thing about using timing belts and pulleys instead of direct drive steppers.
So lets say.....
30x60x6? or so cutting area, 1/2-8 2 start leadscrews, 640 oz steppers geared 1.3:1 using gecko drivers, nice big PC 1/2inch router, and deskam/deskcnc running the show, or at least try it out before we buy it, ive been playing with it and i kind of like it, but i have nothig to base my opinion on. Any thoughts on software for newbies?
motors-$115 x 3
Geckos-$115 x 3
Deskam/cnc+hardware $350
Around $1000 for the 'spensive stuff, i figure $300-$600 for the rest, still not too bad for a larger CNC router with some speed and power. ALOT cheaper than some of the quotes my friend got on the Phone....
Thanks for the help guys..
Dylan
If your cutting wood, you won't need more resolution than the .00125 you'll get from those screws. Adding pulleys and belts justs adds complexity and cost you don't really need. And because steppers lose torque as they go faster, trying to gear for more torque may not actually give you any more torque.Originally Posted by Dylwad
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
May be I miss it can anyone tell me what motors are used and what type of router motor is used with these plans.
uh oh. I'm building this, but down-sized it a bit due to the leadscrews I do have! <grins>
I've got 150 oz-in steppers, a cheapo driver, 5/8" 10 tpi single start leadscrews - have to connect them to a .25" shaft somehow.. I'm trying for better resolution, AND better torque than what I'm used to with the old router..(A "Morph" from **********)(which has 80 oz motors, full steps 18 tpi 5/16" allthread, with homemade delrin nuts with no allowances for backlash whatsoever!) It's as loose as a goose!
..wish I could afford some triple stack nema 34's or whatever?
I just bought a Sherline 5400, so between this home built router and the Sherline I should start learning some of this stuff!
These plans are very good but they are in inches. Can you post a pdf version with all measurements in cm? It would greatly help us all in Europe.
Best regards
George
Athens, Greece
You could volunteer to do it, if you're really interested. 1 inch = 25.4 mm
I do not understand their love to inches either. Especially what they are using to measure torque: lb/in or oz/in or something like that. Nevertheless this has not stopped me to copy their constructions. Imagine if they can make such a wonderful constructions in inches what they could do if they knew metric measurements.
Best Wishes
Alar
We'll I ordered meshcam/mach2, controller and motors from xylotek. And I have a will call pick up for 3/4 " baltic berch plywood on the way home.
I figure its a start.
I just joined the group and the thread. very interesting plans. How hard would it be to add the forth axis (A) to the table. Also is it possable to get a CAD file of the drawings.
Dave
JGRO, Awesome plans Extremely detailed.
I'm not sure if you're still maintaining them, but I noticed what might be a few small mistakes. Some of the pages have an empty quantity block(the number can be found in the parts list anyway). But also, for parts CNC_dtl01 and CNC_dtl02 I believe the stock size is listed at something like 1.5x8.25x16.25, when, unless i'm mistaken, should be listed at 1.5x8.25x32.5. Those numbers are just off the top of my head, but you get the idea.
Hey guys,
Were coming along on the router, got the ends of the 1/2-8 2 start acme turned down and drilled/tapped, and made a tap out of it for 6 delrin blocks, very smooth. We will post some pics soon.
Anyone want to help me out with some math?
Also, when you figure out your resolution, do you go off of 200 steps per rev, or 2000 when your microstepping?
heres the math...
1/2-8 2 start- 4 turns per inch
40,000 steps per second
8000 steps per inch
What RPM will i get at 40k SPS? I came up with 1200
How many IPM am i looking at? 300?
From what ive read 1/2 leadscrews start singing around 450-500 RPM so im thinking 100IPM shouldnt be a problem on this rig.
Am i totally off on my math? anyone have some formulas to use to make life easier?
Thanks,
Dylan
one more thing, is there any way to be able to see more than 5 posts per page on the forum? its kind of annoying when im used to 50 or so per page on ezone.
Originally Posted by Dylwad
You can change the default thread view in the usercp.
If your using geckos with 10x microstepping, then you'll have 4 tpi x 200 steps/rev x 10 (microsteps) = 8000 steps/inch, like you said.Originally Posted by Dylwad
40000 steps/second * 60 seconds / 8000 steps/inch = 300 ipm, @ 1200 rpm.
Leadscrew whip is dependant on length, and how it's mounted.
The speed of the machine can be limited by many factors. Motor torque, voltage supplied, friction. Because stpper torque can drop off quickly, especially at lower voltages, you may not have enough torque to get to your theoretical 40,000 steps/s.
Depending on the torque of the motors, you might get 100ipm rapids, but may not have enough torque at that speed to cut materials.
What size motors (ratings) , power supply and what drivers are you using?
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Wow, Great reply,
The motors are 640 oz 2.3 volt 5.5 amp nema 34 www.homeshopcnc.com The leadscrew nuts are 1.5 inch delrin, doubled up on each axis. one of the leads is 6 feet long too....hopefully the 3 inches of nuts and some tension will help to smooth things out.
Power supply im looking at 48 volt 12 amp units, but we may build our own, so about 20 times motor voltage.
The leadscrews have dual bearings on each end, and will have a bit of tension to them.
Were not planning on cutting anything anywhere near 100IPM, but it would be nice to have some decent rapid speed.
I just realized the deskcnc controller has a 125000SPS max......http://www.deskcnc.com/controller2nd.html
So, one more time, this is the rundown
cutting area around 5'x3'x5"
640 oz steppers
z axis geared 1.5:1 or 2:1
1/2-8-2 start leads
gecko 201's
48 volt 12 amp supply
deskcnc software and controller
full size PC router
Mainly cutting 1/4"~1.5 inch foam.
gas pipe rails on x and y ,X is supported in the middle, and THK style on the Z
pipe adjustment blocks are 3/4" aluminum tapped for adjusters.
sound like it will work?
Thanks,
Dylan
I bet you'll want to after you use it for awhile. I wouldn't think you'd have a problem cutting foam at that speed, as there would be basically no load on the spindle.Originally Posted by Dylwad
Sounds like it should work OK, but the power supply might be a bit marginal on the current rating. Might be OK, though.
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)