MechMate CNC Router Forum

Go Back   MechMate CNC Router Forum > Personal Build Histories > MechMates already cutting
Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Reply
 
Thread Tools
  #31  
Old Thu 05 July 2012, 02:25
litemover
Just call me: Chris
 
Auckland
New Zealand
Thank you for clarifying that. Very sorry for not reading the manual first.
CC
Reply With Quote
  #32  
Old Tue 10 July 2012, 18:26
litemover
Just call me: Chris
 
Auckland
New Zealand
Hi, I've been reading through all the motor threads and thanks for all the info on them. I'm still having quite a selection difficulty with the motors.

My first choice is to use the PK296A2A-SG7.2 as recommended, then I heard the PK299 - F4.5a with a 4:1 belt drive was cleaner and less backlash. But then I heard that the PK296-F4.5a running bi-polar parallel were just as comparable and delivered 1000ipm. at 1200 oZ of holding tourue. This is a smaller motor but faster curves, less torque at $157 USD.

What I'm looking for is the ability to cut cleanly through plastic, aluminum, and MDF/Wood. With as little sanding as possible required. Can anyone suggest the optimum Oriental Motor config for a 5x10 table running a 4hp 100mm Chinese Spindle please? I have G203V.

Thanks,
Chris
Reply With Quote
  #33  
Old Tue 10 July 2012, 21:49
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
Before you order your motors let me price them as well. I am now setup to sell Oriental Motors direct. I can do the PK296-F4.5A for $139.00 each plus shipping. I will be away from my office though next week and not able to ship any stock parts. I will only be able to drop ship. All OM are drop ship items.
Reply With Quote
  #34  
Old Wed 11 July 2012, 00:03
litemover
Just call me: Chris
 
Auckland
New Zealand
Quote:
Originally Posted by MetalHead View Post
Before you order your motors let me price them as well. I am now setup to sell Oriental Motors direct. I can do the PK296-F4.5A for $139.00 each plus shipping. I will be away from my office though next week and not able to ship any stock parts. I will only be able to drop ship. All OM are drop ship items.
Does this mean that any questions I ask about motors, etc, are moderated and moved to this one build thread? Kind of defeats the purpose of having a forum.
Reply With Quote
  #35  
Old Wed 11 July 2012, 05:21
darren salyer
Just call me: Darren #101
 
Wentzville mo
United States of America
Seriously???
Exactly how does this defeat having a forum?
Your posts are all in your build thread, instead of spread throughout the forum
Yesterday, you asked the exact same question in two different spots moments apart.

Asking the same question multiple times in different spots will get you an answer no quicker.

Believe me, going back later to reference an answer to a question will be a huge time saver.
Mike is offering to try to save you a few bucks.
Read my build thread, my motor choice and power supply is listed within and I'm very happy with the choices I made.

Enjoy your buld.
Edited to add: You've been asked nicely by two people to refrain from quoting posts in your replies, I'll nicely ask as well.
Reply With Quote
  #36  
Old Wed 11 July 2012, 06:41
litemover
Just call me: Chris
 
Auckland
New Zealand
That's simply untrue, I asked this question in the motors area where it was, before it was moved here, it defeats the purpose by having a communist sensored forum in the place of a free thinking open one., one where ideas are exchanged, experienced shared , and no question is too stupid or boring. You people sure do have a lot of time on your hands to be bothered by some inquisitive newbie's posts dirtying up your perfect forum. I'd appreciate the right to post in any section I see fit without the whining or censorship. Nif this place is too childish to afford me this basic privilege,a dn my posts continue to get moderated into my own thread, I' ll quite happily shitcan this project and do a different one.
Reply With Quote
  #37  
Old Wed 11 July 2012, 06:43
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
If you ask all of your questions in your build thread it helps us all keep track and help you with your build. I moved the post trying to keep us all in line with what your working on. So if you would like to chat with me just let me know and I'll give you a call. All we want is for you to have a successful build. You can see with over 100 machines registered that this format works and works well.
Reply With Quote
  #38  
Old Wed 11 July 2012, 13:28
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Chris, that childish tantrum was uncalled for.

This forum has 25 000 registered members. It is a popular reading place because it is relatively easy to read. You have decided it is your right to spit on the floor of our house. If this were still my forum, I would expect an apology or I would kick you out. Your absence here wouldn't cause a ripple .... in fact it would calm the water.
Reply With Quote
  #39  
Old Wed 11 July 2012, 14:50
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
Quote:
Originally Posted by litemover View Post
I' ll quite happily shitcan this project and do a different one.
If you decide to build a MechMate, its not for our benefit - it will be for yours. We have built our machines by learning from the forum and from others that walked the path before us - it serves us well. Accusing us of being commies and closed minded will not get you the help you seek, I agree an apology is in order.
Reply With Quote
  #40  
Old Wed 11 July 2012, 18:24
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Ditto. (always at least once a year this troll behavior pops up)

Chris. There are many people here, like myself, that dedicate our experience to sharing with the forum on a daily basis since 2005. If you see the folks that are chatting directly here to you hold some of the lowest serial numbers. We are the beta group. We are the voice of experience that have built and watched others build 100+ machines.

If you would like sage advice, it's here.

Please respect the platform here, we all do this to keep it professional, friendly and accessible to all.

Last edited by smreish; Wed 11 July 2012 at 18:33..
Reply With Quote
  #41  
Old Wed 11 July 2012, 21:56
litemover
Just call me: Chris
 
Auckland
New Zealand
Sorry for the frustration folks. It's quite a lot to swallow, especially being in a rush to get the parts. Suddenly not being able to post for help and advice, with exception to this solitary thread of mine, makes the whole project feel quite daunting, sort of being restricted to a small raft in an ocean of unfamiliar territory. To me, this is a considerable investment for not being quite sure of my ability to produce the end product. My lack of confidence has me feeling for the for the walls a bit more than usual. So I apologize for the frustration, and for asking too many questions.

Thank you for the support.
Chris.
Reply With Quote
  #42  
Old Thu 12 July 2012, 05:11
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
Well Chris amny feel that way at first and once they do dive in they just do the work in pieces and look up one day and they are cutting
Reply With Quote
  #43  
Old Thu 12 July 2012, 07:40
bolingerbe
Just call me: Bryan #54
 
Clinton(Tennessee)
United States of America
Chris, I felt intimidated when I started. But I had read some post "Not enough" but what I found reading the post is if you ask the questions you will have everyone trying their best to help. I have made some changes to my setup by adding a 4th axis, changing the operating voltage of my motors and the addition of a removable sections of my table to allow Vacuum hold down or the Tee slots I original installed. Most if not all of this information is contained in the Forum. Some of the people answering the questions are also found on throw out the web doing the same thing, helping others. Trust me I did not complete my machine without help and every time I asked for assistance someone stepped up and answered the question at hand.
Reply With Quote
  #44  
Old Thu 12 July 2012, 18:17
Zouave
Just call me: Eric #115
 
Sacramento, CA
United States of America
A lot of us also subscribe to specific threads, including build threads, so get email notifications that you have posted, and can see your question immediately there. Posting a new thread only gets noticed by checking the forums for new threads.
Good luck on your build!
Reply With Quote
  #45  
Old Thu 12 July 2012, 23:56
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
A lot of us check last day and it is frustrating to open a "new" post, wait for the whole thread to load, and then see at the bottom it is a duplicate post.

If a particular user becomes irritating, some would put that user on ignore, and make sure time is not wasted with irritations.
Reply With Quote
  #46  
Old Fri 13 July 2012, 14:27
litemover
Just call me: Chris
 
Auckland
New Zealand
Ok no worries. Thanks for the reassurance. Just don't want to start building this and get stuck, which being so far from the US tends to happen with parts especially.

Still just trying to figure out what motors will make the finest cuts that require little sanding, the OM geared, or the ungeared. Anyways, thanks again everyone for the help.
Chris.
Reply With Quote
  #47  
Old Fri 13 July 2012, 16:23
darren salyer
Just call me: Darren #101
 
Wentzville mo
United States of America
It is my understanding that the direct drive motors with the belt drive reduction offers the best resolution,but someone may chime in to dispute that.
Reply With Quote
  #48  
Old Fri 13 July 2012, 18:30
KenC
Just call me: Ken
 
Klang
Malaysia
To be very specific. Direct drive motor with a belt reduction is the most cost effective mean to increase mechanical transmission resolution on top of the electronics means e.g. micro-stepping.
A stock gear box with the right specification will achieve the same performance but the cost is a lot higher.
BTW, even with home made belt reduction, the cost is definitively more than a few dozen of hot dogs, timing belt pulleys don't come cheap especially when you have to make 4 set of them. but will still be cheaper than buying a single OM with 7.2 gearbox.
Reply With Quote
  #49  
Old Sat 14 July 2012, 22:58
litemover
Just call me: Chris
 
Auckland
New Zealand
Thanks Ken,

I'd be happy with whatever option delivers the cleanest cut, which requires least sanding, despite the price, within reason of course.
Chris
Reply With Quote
  #50  
Old Sat 14 July 2012, 23:39
KenC
Just call me: Ken
 
Klang
Malaysia
"Cleanest cut" is such a general, subjective & illusive goal...
Reply With Quote
  #51  
Old Sun 15 July 2012, 00:10
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
In all three groups of users (those with gearboxes, those with belt-drives and those with direct drives) some will get good cut quality and some will get poor cut quality, with swings between good/poor happening from day to day. There is generally consensus that direct drives can be improved by gearboxes/belts. But there is no hard evidence that a belt always beats a gearbox, or vice versa.
Reply With Quote
  #52  
Old Sun 15 July 2012, 02:52
KenC
Just call me: Ken
 
Klang
Malaysia
And there are those (yours truly) who are too lazy to "upgrade" their direct drive even after 2~3 years...
"You gotta sand anyway..." Is one's excuse...
Reply With Quote
  #53  
Old Sun 15 July 2012, 16:59
litemover
Just call me: Chris
 
Auckland
New Zealand
Thanks.

I think I get it now. One last question, does it hurt performance to have too much torque? In other words, would it be too big to go with an OM 299 vs a 296 OM? Then put a gearbox or belt drive on it? Also, is there any benefit to going with .72 degree or .90 degree motors to get finer edges?

Almost there with motors.
Thanks,
Chris
Reply With Quote
  #54  
Old Mon 16 July 2012, 01:34
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
see here: http://www.mechmate.com/forums/showthread.php?t=255
Reply With Quote
  #55  
Old Mon 16 July 2012, 04:34
litemover
Just call me: Chris
 
Auckland
New Zealand
Thanks, I read that one, and was staying away from the larger 1200+ oz motors. But did wonder about them. Really interesting and informative post though.

Thanks,
Chris
Reply With Quote
  #56  
Old Mon 16 July 2012, 23:39
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Chris,
I assume that you have decided whether to wire half-coil or bipolar? Because that affects your torque. You must have, because you've decided your power supply, right?
Just thinking...
Reply With Quote
  #57  
Old Tue 17 July 2012, 06:55
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Chris, let's do some math. A stepper motor driven by a Gecko stepper driver makes 2,000 steps per revolution. Finding how "fine" or "small" each step is, on an ungeared motor is simply knowing the diameter of the spur gear and then dividing that by 2,000.

Common spur gear sizes in the United States are 20-tooth (1" diameter), 25-tooth (1.25" diameter) and 30-tooth (1.5" diameter). So, minimum (finest) per step movement on an ungeared motor would be 0.0015708" for a 20-tooth, 0.0019635" for the 25-tooth, and 0.0023562" for the 30-tooth.

Using a 4:1 belt-drive would reduce that distance by 4X, for a minimum per step movement would be 0.0003927", 0.000490875" and 0.00058905".

Mechanical "wobble" or flexing or "slop" in the machine will keep you from getting that resolution unless everything on your machine is tuned perfectly. A MechMate is much "stiffer" than my Shopbot PRT-Alpha was, but I think that if you ran a CNC router back and forth about 10" several times with dial-indicators on both ends of the travel that you would see several thousandths of an inch variation with each move. That would show you the "repeatability" of the machine.

We all know that wood changes dimensions because of humidity, so cutting multiple parts that have a few thousandths of an inch variation is not a problem because next week or next month, the wood will be a slightly different size anyway.

Metals and plastics are highly resistance to humidity, but they still are affected by temperature. Even the best machinist can't guarantee that a precisely cut piece of metal will have the correct size if that piece of metal is measured at different temperatures.

What I'm trying to say is that you shouldn't just do the math and then expect your cuts to be as "fine" as the math tells you that they will be. Machine "looseness", chip load, cutter flexing and all the other little "gotchas" will affect the quality of your cuts. I was extremely disappointed with the cuts that I got with my Shopbot, especially on curves; however, when I learned that each type of wood seems to have a sweet spot with feeds and speeds and cutters, things improved, i.e., operator inexperience was causing a lot of problems. After I built and installed 3:1 belt-drives on the Shopbot, cut quality improved dramatically. You'll probably find the same thing with your machine. Operator inexperience will give you poorer quality than you expect, but things will get better as you learn and gain experience.

On my best days, I was happy to get cuts where the gap in any joint was less than the thickness of a piece of copy paper (about 0.003"). When that happened, I knew that all the flexing was working in my favor.

Now, to your question about the PK296 vs the PK299. If you're going to add a belt-drive, the PK296 is plenty of motor. If you study the electrical specs on the Oriental Motor website and compare the PK296-03, the PK296-F4.5 and the PK296A2A-SGxx, you'll see that the motors are the same electrically. The F4.5 has eight leads and the other two motors have six leads, so the F4.5 can be wired either half-coil or parallel. The F4.5, with a belt-drive, can be driven harder than the SGxx motor with a gearbox. That's because the gearbox is not as mechanically robust as a belt drive, i.e., if you drive it harder than Oriental Motor recommends, it will wear out sooner than expected.

The Keiling motor that Mike (Metalhead) sells is an excellent motor. I tested one for him a while back and ran it side-by-side on my test bench with a PK296-F4.5, a PK299-F4.5 and a PK296B2A-SG3.6. ALL of the motors were excellent. ALL of the motors (when used with the proper power supply) were more than adequate for a typical CNC machine.

Build your machine. Learn how to use it. Make some money with it and then, after you know exactly what needs improving, you can modify it by adding different motors, linear rails, or anything else that allows you to make the cuts that you need to make.
Reply With Quote
  #58  
Old Tue 17 July 2012, 14:22
litemover
Just call me: Chris
 
Auckland
New Zealand
Wow, thanks for that incredible information Mike. That really helped a lot. No I haven't figured out the half coil thing yet either Red. When the gearbox wears out on the SG7.2 version, is it easily replaced, or does one have to toss the motor out and start from the beginning? Also, can you upgrade the gearbox to a belt drive later (take off the gear box)?

Linear rails/motion bearings sound really good on the Z axis at least. I looked at the carriage design and am not sure I can reproduce the amount of accuracy you guys have on it. We'll see.

Thanks for the info guys.
Chris
Reply With Quote
  #59  
Old Tue 17 July 2012, 14:53
Zouave
Just call me: Eric #115
 
Sacramento, CA
United States of America
I know it is intimidating, i had the same concerns going in. But the reality is that if you follow the instructions here, and go about it carefully, you will get the same results others have. I want sure going in, and i am really happy with where my build is right now.
Reply With Quote
  #60  
Old Tue 17 July 2012, 16:43
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Use the half-coil wiring.

The SG7.2 is essentially a single, non-serviceable unit - the motor shaft itself is cut into a helical gear, so you cannot remove the gearbox and use the motor. You can check with OM, but I'm pretty sure you can't replace the gears either.

The Z axis, in the modern six wheel version, with the offset bushings is not difficult to make accurate. Might even be easier to get plumb and square than linear bearing rails, which will only be as accurate as your mounting of them - which you'll have to design.
Reply With Quote
Reply

Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Just started the build - Auckland, New Zealand wheelygood Construction started, but not cutting yet 24 Sat 03 April 2010 01:01


All times are GMT -6. The time now is 05:53.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.