Help get me started in the right direction!

[freezer]

I hare read through many diy cnc projects and even was lookng at Kleinbauer site... (was emailing him but i guess i asked too many questions). Anyway, I am wanting to build a cnc router to help me with my scrollsawing. Maybe do some carving into some relief carving as well...

I am on a very fixed budged and can not afford to buy the wrong stuff.

I would like a 2'x2' cutting area with a shopvac hold down. I do not have the metel working skills that i see many of you guys are really!!!! good at.

Can you recommend a design or one to stay away from?

Thx,
Rod

[gmfoster]

Well I would not buy anything from John again. I boiught a set of plans from him and they are are minimual but functional. However if you have followed his site for a while you will have noticed that he is very predicitable in that he is constantly changing his mind. I wrote a short note about his plans on another section of this board. He took real offense to it and has refused to answer any questions from me or to let me read his forem.

So much for customer service..

I also bought the "Hobby CNC" plans and found then both simpler to build and the parts more available. And Dave has never refused to answer any questions.
And Dave still posts on most of the boards as opposed to John who has been kicked off or left most of the groups he doesn't run himself.

Also I think in somehing like this statements like I can't afford to not do it right the first time are setting you up for a fall. The first system should always be looked at as a learning experence.

Garry

PS I about have the sytem completed at this time. If you buy the 7th Sojourn drop me an email and I'll give you some hints about things that can be improved.(IMHO)

[freezer]

Originally posted by gmfoster Also I think in somehing like this statements like I can't afford to not do it right the first time are setting you up for a fall. The first system should always be looked at as a learning experence.

Garry,

Here is what i am conserned about... If i spend $500 to $1000 bucks on this project and it is a complete failure, I would not have the funds to do it again... Also why reinvent the wheel? If this part works better than that part... I would sure like to know before I get started. I was reading that some plans available call for part that in reality do not work as expected.

Also in your opion do "hobby cnc's" have the accuracy to do what i am looking at doing?

[freezer]

Also, why do sites say:

"Longer travels and larger cutting tools are not recommended!

PLEASE Stop Asking!"

what is the difference in having a 12in bed ver a 15 or 18 or 24?

[buscht]

I am developing a CNC scrollsaw. My findings are that you need to move the part around in an X-Y fashion through a spiral blade.

You don't need any Z axis for this. (Potential savings), but you won't be able to carve.

In order to do this, I recommend make a machine that moves the table in both the X and Y directions. If you have a gantry machine, it will still work it just makes it harder to clamp the part.

What you absolutely don't want is a design where the table moves in the X and the router moves in the Y. You cannot clamp a part and move it through the scroll saw.

[freezer]

WOW!

How did you get a table to support your work yet freely move around a small blade?

[Hobbiest]

With some good scrounging, it is very possible to build a router table, including electronics for $300 or less. Accuracy will not be upper escillon (did I spell that right?), but it will be a functional, well working table. Why do you want to use a scroll saw instead of router spindle BTW?

[freezer]

Originally posted by Hobbiest Why do you want to use a scroll saw instead of router spindle BTW?

Actualy, I had intended on using a trim router that i have laying around i dont use for anything. buscht said he had developed a cnc scroll saw.

I have been doing scroll work that takes me about 4 hr per. It is in 3/8 oak so i cant stack them to the the cuts i need although, most cust could be made with a router only about 10% would need to be done by hand on the scrollsaw and those would be rather quick cuts.

After reading comments about the man many call crabby i have reservations about buying his plans. Although, I believe I could build any of his without plans I was going to buy a set anyway.

I understand that his plans require parts that are not available everyware.

I have a design in mind that would be a fixed cutting bed and a 3 axix cutting tool. The bed would use a shopvac hold down system.

I have read about the gas pipe guides, drawer slide guides, and seen some metel work I could only dream of having the skills to accomplish.

Let me just ask a few specific quesions to begin with:

What slide mechinisum do you recommend?
What size of stepper motor do you recommend?

The pic's i have seen it shows the pipe/rods going through and being adjusted by a 4 screw block... what do you do to keep the pipe from sliding back and forth?

[chuckknigh]

Also, why do sites say: "Longer travels and larger cutting tools are not recommended! PLEASE Stop Asking!" what is the difference in having a 12in bed ver a 15 or 18 or 24?

It's very simple. Have you ever heard the term deflection? Increasing the length of a beam from 12" to 18" is a 50% increase in length. 24" is a 100% increase in length...double!

Things like rails get less stiff, as their length increases. Or, to say it more precisely, they can flex more...

By making them longer, without taking into account other factors (basically making them larger in diameter and/or of a stiffer material) you will make them more flexible.

Practically speaking, you will reduce your machine's accuracy if your carriage can move laterally...longer rails allow that kind of movement.

-- Chuck Knight

P.S. As to what you should build, look at what you want to make, and the accuracy requirements for it.

I wanted to make clock gears and that sort of thing...small, but precise. Others may want to cut out large "yard art" signs...big, but less of a need for precision.

And, this is going to sound very silly, but just get something moving. Build a first machine, as a learning experience. A lot of the parts, such as the motors and driver boards can be recycled to an upgraded machine, later on. The basic mechanicals of a "first machine" need not cost much at all. Some MDF, some gas pipe, some allthread rod, some secondhand Rollerblade bearings from the local Goodwill store, etc.

Also check the "scrap bin" at your local lumberyard...Home Depot, especially, has some good deals on their leftovers. I got some MDF scraps, from which I built my entire machine (and still have some left over!) for $2, total!

[freezer]

Deflection... I would think that a 3/4" gas pipe would not deflect that much over 36" in this setup...

That is true about just do it, I have a 1/2 sheet of mdf in the shop leftover from a previous project. I usually over think things before i get started.

What size of steppers should I get?

[chuckknigh]

Balsaman (Eric) has one of the better known machines on this forum. He designed it as a moving table, fixed gantry unit, and it was made primarily of MDF. He's since built a MUCH larger machine from aluminum, but his first machine is an excellent example, and a well proven design.

http://www.cnczone.com/showthread.php?threadid=228

That shows a pretty good picture of his machine. He used 100 oz-in steppers, and had a working area of 12x18", I think.

Now, of course you can just go and buy them, but using the "hacker" and "dumpster diving" approach, you can find them much cheaper.

A cheap source for these steppers is to find some old junked HP LaserJet printers. Models I, II, and III all used identical steppers, all 100 oz-in. There is 1 motor per printer. For reference, I routinely pick these printers up for less than $1 each...the highest I've seen them recently (barring one single extreme example) was $15 each. HINT: If it's missing its paper tray and/or toner cartridge, all the better! You won't need them, and it reduces the printer's value to nearly ZERO!

-- Chuck Knight

[gmfoster]

Freezer Said
Garry,

Here is what i am conserned about... If i spend $500 to $1000 bucks on this project and it is a complete failure, I would not have the funds to do it again... Also why reinvent the wheel? If this part works better than that part... I would sure like to know before I get started. I was reading that some plans available call for part that in reality do not work as expected.

Also in your opion do "hobby cnc's" have the accuracy to do what i am looking at doing?



Well if you learn something its not a complete failure. And if you think there is no difference in a 12 inch length and a 36 inch length then you have a lot to learn. Rigidity is the key and shake a toothpock and see how much it deflects, then a .5 inch dowel 36 inches long. The .5 in dowel will flex much more than the much smaller tooth pick.

Also it wouldn't be a total loss as if you build it right iit can always be sold or many of the parts reused. And I think you could build a machine like Johns for 2-300 dollars . And if you would use threaded rod to build one like the Hobby CNC for not much more. In either case the controller and the motors could be resold or reused. I think the real answer is that you have to get started and I know that if I started and spent a kilo buck and it didn't do what I wanted I wouldn't be a happy camper but if all I lose is 100.00 worth of MDF and plywood and 30 bucks worth of threaded rod and hardware I wouldn't see it as any great loss. I Have spen about 300.00 dollars so far and have enough that when I get done I will have a 7th Sojourn and a hobby CNC system.

the 7th sojourn is about finished and I have the parts for the hobby CNC system.

As I say if you are smart enough to never buy or build something that you want to replace you are a lot better than I.

Garry