Want Slower Alpha Move Speeds

[gus]

I have a application where I need to input a slower move speed than the .05 that the software will let you do. Anyone have a work around for that?? Called ShopBot and they are thinking on it. "You are not the first guy to ask that." but did not have a ready fix for it. I do not want to go with gearing. The final drives off my old skidder are just too heavy. ;>)

[Brady Watson]

Ted,
The easiest way would be to get new motors with a 3.6, 7.2 or 10:1 ratio gearbox on them & the appropriate Alpha driver. This would be a bit of an investment, but it would effectively give you superior low speed performance and gobs of low-end torque. This arrangement would actually be a great upgrade for the standard Alpha tool, because in reality, 99% of users really don't need to jog at 30 IPS. Going with gear reduction would also increase the resolution of the machine.

I am assuming that by 'gearing' you are referring to a reduction in pinion diameter, which is pretty much undesirable. Without changing the final drive ratio, the motor will not have good low-speed performance and the motor will probably run hotter than it was intended to.

-Brady

[gerald_d]

Maybe your application will allow fine thread screws?

[gus]

Brady, I was looking more for a software way around the issue. The project will not support a large investment in money. At least not at this point. In the process of testing a concept I found the low end limit on feed speed to be a problem. I need to work this out before I can move on to implementation.

Gerald, Fine thread screws? I just found out that not all nuts have 4 sides on the head. If you are talking ball screws it is the same money thing.

In both cases your ideas are valid just not cost effective for me.

[Brady Watson]

Ted,
I don't believe that a 'cost effective' solution using Alpha hardware and ShopBot software exists for you at the moment. You just can get smooth movement moving any slower than your current hardware allows.

What's the application?

-Brady

[stevem]

I believe the Alpha hardware will work with Mach2 software. The Alpha drives accept step and direction signals. This should be a simple $150 solution.

[gerald_d]

Ted, if your application is that slow, your wear-and-tear rate will be low and dust will be minimal, so there is potential for using plain old threaded bar from the hardware shop. (Shaft "whip" is not a problem at very low speed). But the accuracy will be low, because that threaded bar is not really tightly controlled for "threads/inch".

[gus]

I do not want to get into changing the Bot as this is only one application and not even something I am using for real production as of yet. I may use Bot to prove out the process and if it is something I will be doing I will make up an X,Y table that will do what I want. Thanks for the ideas guys.

Brady "You have mail"

[bill.young]

Hey Ted,

Slower speeds for the Alpha are on the list to work on after we get the next release out. Just out of curiosity, how much slower do you need to go?

Bill

[mikejohn]

How about very long ramping distances and slowest possible ramping speed?
..................Mike
mumble mumble,PRT,mumble mumble

[gus]

Bill,
So that would be real soon? Being able to input a value of .02 may be good enough but if you are going to do it you need to ask yourself just how slow can it go. Within reason of course.But then at some point in time the speed I can get now was the limit of reason right? I am not being critical here you have to stop someplace.

Mike, I have never messed with ramping. Can you ramp around a small arc?

[bill.young]

Hey Ted,

There is a new software release coming out soon but this won't be in that release...it'll be worked on for the next one.

Bill

[richards]

Ted,
I'm wondering just what you're cutting. It seems to me that at those slow speeds you're going to have to have low RPMs on the router/spindle to keep from burning the material that you're cutting.

On my Alpha, I have a really hard time going below 0.5 inch per second at 5,000 RPM without burning up the cutters.

[gus]

Mike,
.024 spiral tooth saw.

[richards]

Ted,

That explains everything. I've never used anything smaller than 1/8-inch, with 99% of my work being cut with a 3/8-inch cutter. With the big cutters, it's easy to push them hard and fast.

[Brady Watson]

Mike...note that he said 'saw'...not bit.

-B

[richards]

Are we talking scroll saw blades?

[gus]

Mike,
you have mail

[3d_danny]

Ted,

I am curious about saw blade/bit that you are using.
I have wanted to try cutting very fine lines into some material that I have but havent found a suitable bit.

I would like to hear about your project, if I may.

Dan
(dandunn at bellsouth.net)

[trakwebster]

Hello, Ted,

I'm curious about three things, please ...

1) What is a 'spiral tooth saw'?

2) How do you mount a saw blade?

3) I will be having a (repeating) need to cut slots, both parallel and also non-parallel lines, which are nominally 0.023" slots. I had been planning to research dental bits to see if they would work. Do you think your application would work in my case?

(These are to be fret slots in fretboards of rosewood and maple, with some frets parallel in the usual way of guitars, and some in the Novak 'fanned-frets' manner. You can see a picture of our Novak fanned fret instrument here -- http://megatar.com/english/Models/ToneWeaver/toneweaver.html)

[trakwebster]

Ted,

Since I do not know what a spiral tooth saw is (yet), my suggestion may be inappropriate. But if you have any choice in the diameter of the blade (or bit), and if you then use a smaller-diametered blade (or bit), then the speed at the cutting edge would be less. Probably this isn't helpful, but I thought to mention it in case it had been overlooked.

[gus]

Arthur,
Spiral cut scroll saw blade. The smallest I have seen is .024 and would have a kerf a bit more. So a .023" cut no. But close. I have a drawer of dental bits I picked up years back with the intent of drilling PC boards. I have an adapter shank .5" that uses ER-11 collets I just have not gotten around to getting a collet small enough to chuck up the bits and try them. They have two shank dia. They are ball and end mill type cutters and the taper on the shank will limit your max depth of cut. They are something I want to play with though. Sharp little buggers.

[gerald_d]

For such fine, shallow, straight, open-ended, cuts as in fretboards, have you considered "dragging" a blade across the work? Something like a horizontal saw blade mounted at a very slight angle so that the last teeth cut more than the first teeth. Tricky for angled frets, but should be easy for the parallel ones...