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stepper & driver
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Douglas Pollard
Hi Bellendo
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I will take your advice on the two motors driving the x axis and will use instead a jack shaft to drive sprockets on both sides of the x axis and will use chain on the Y axis as well. I will be making parts during the winter as well as finishing up my building. Assembly will start in the spring. In the meantime I will also build a very small three axis engraver-router to learn what the building of a cnc machine is all about. I have some small stepper motors and an old 486 Dell computer to run it. and a bunch of shafting out old dot matrix printers too. I don't want to reinvent the wheel on this so I will probably buy a set of plans to work from. Any advice as to what set of plans would be easy to build using as much of the hardware that I have would br helpful. I would like to thank you and everyone else for their input. Doug - Original Message -----
From: "ballendo" <ballendo@...> To: <CAD_CAM_EDM_DRO@...> Sent: Wednesday, November 26, 2003 3:29 AM Subject: [CAD_CAM_EDM_DRO] Re: stepper & driver Doug,timg@... Moderator: pentam@... indigo_red@... [Moderators]aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble. sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (). Version: 6.0.536 / Virus Database: 331 - Release Date: 11/3/03 |
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Doug,
Sounds like you've considered the implications of the Oak subframe, and it will likely work since you're willing to sacrifice some accuracy. I personally don't think using two motors on a given axis is a good idea... (Mariss of Gecko has also stated the problems of such a choice.) Having said that, there are a large number of machines both hobby and commercial which successfully use two motor drive. But I wouldn't... If you're going to use chain for the long axis (X, though some mistakenly call this Y); IMO you should also use it for Y. You will get FAR in excess of your desired travel rates, IME. Easily 240 IPM with 2A "cheap" drives, 34V power, size 34 double stack motor, and 4:1 reduction. For cuts in the 120IPM arena... BTW, go ahead and use a screw for the Z, it makes things easier. Good luck, send pics when you're done! Ballendo --- In CAD_CAM_EDM_DRO@..., "Douglas Pollard" <dougpol1@o...> wrote: Hi cnc folks,already have the wood "free". with it screwed and glued together it will be light. Several coats of epoxy will solve most of the expansion problems where moisture is concerned. I plan to use metal ways for accuracy and ease of movement. The x axis rails will be tied together with metal bars so the expansion of the wood will not change the y axis width. Only one rail will be bolted tight to the wood the second will offer support only but will not act as a guide. I have 50 ft of roller chain it is about the size of bicyclechain # 10 I would guess. I am thinking that I will put one piece on each side of the gantry to drive in the x axis. Each side will be driven by a # 33 frame motor {Ithink this is the right designation?} It's close anyway. I understand that. I that I can hook them up in series. I would consider 30 to 50 inches a min. feed rate with 100inches rapid traverse a complete success anything faster would be a bonus. The Y and x axis would probably be driven by lead screw. Isee no reason that a second motor on the y lead screw could not be added if needed also hooked up in series. Any comments on the practicality of hooking motors inseries would be a big help. Do you get double the power? Do they interfere with each other? Does this overload the drivers in some way. I assume power supplies have to be larger? I have seen reference to this practice on line but no realdetail as to, how. Doug |
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Have you ever considered creating two separate x-axis assemblies and
slaving them together using your CNC controller software? You'll have to go through the trouble of making the two complete axis assemblies but you won't have to worry about the gantry getting out of alignment. Also it allows you to run two midsize motors instead of one big one to push the gantry along. As far was the oak, sealing it with epoxy might be overkill, you might want to use oil based urethane for floors. It builds well, and it's spray able (even through a garden sprayer) that way you'll be sure to get all the nooks and crannies. Tie that with some brass accents and it will look great :) Just an idea. Aaron Moss www.IndustrialHobbies.com --- In CAD_CAM_EDM_DRO@..., "Douglas Pollard" <dougpol1@o...> wrote: Hi cnc folks,already have the wood "free". with it screwed and glued together it will be light. Several coats of epoxy will solve most of the expansion problems where moisture is concerned. I plan to use metal ways for accuracy and ease of movement. The x axis rails will be tied together with metal bars so the expansion of the wood will not change the y axis width. Only one rail will be bolted tight to the wood the second will offer support only but will not act as a guide. I have 50 ft of roller chain it is about the size of bicyclechain # 10 I would guess. I am thinking that I will put one piece on each side of the gantry to drive in the x axis. Each side will be driven by a # 33 frame motor {I think this is the right designation?} It's close anyway. I understand that. I that I can hook them up in series. I would consider 30 to 50 inches a min. feed rate with 100inches rapid traverse a complete success anything faster would be a bonus. The Y and x axis would probably be driven by lead screw. Isee no reason that a second motor on the y lead screw could not be added if needed also hooked up in series. Any comments on the practicality of hooking motors inseries would be a big help. Do you get double the power? Do they interfere with each other? Does this overload the drivers in some way. I assume power supplies have to be larger? I have seen reference to this practice on line but no realdetail as to, how. Doug |
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