Threading

[kubotaman]

I know it can be done but am asking help. How can a person make threads with a ShopBot? I would imagine you would use a pointed bit but what would the best way to lay out the threads??

[Gary Campbell]

Daryl...
Are you looking to cut inside or outside threads? 3 axis work or do you wish to use the indexer?

Personally, I would hand code the operation. Its the easiest way for all options. Most of the design suites do not handle this as well as math does.

[kubotaman]

Gary, it wouild be outside threads and of course using the indexer.

[tuck]

*whew*

I'm no help but I do want to say that the mathematical implications boggle my mind! :eek:

Keep us posted!

[myxpykalix]

Daryl,
I wrote an indexer app (with the help of a programmer) to make spirals a few years ago. Although I haven't used it in a few months I could look at it and see if in combination with the right bit I could use it to make threads which is just a compressed spiral anyway, right?
Check out this vid:
http://www.youtube.com/watch?v=jSy8PGj2eDU
for grins, check out the indiana jones vid too...:eek:

tell me your deminsions, ect and let me see if i can send you some files. Contact me via my email. I think you still have it? Look in my profile

[Gary Campbell]

Daryl...
IF there is a spiral flute tool, you should be able to make it work, using the parameters for your threads, if not here is the math. I am using variables so that you can substitute either your numbers or enter values for those variables in a partsfile.

Given:
assumes X parallel indexer
assumes cutting head has unimpeded access from current location
assumes axis 4 is at zero


&safe_z = (obvious)
&depth = cutting depth of threads
&length = length of threads
&tpi = threads per inch
&y_pos = indexer Y centerline
&x_pos = X start position for threads
&movespeed= XY move speed
&revs = number of indexer revs to cut threads

IF a real value for all these are entered in a parts file, then the following will cut threads:
&movespeed = 1 / &tpi '(returns 1 rev per second) (watch you dont go below .05)
&revs = &length * 360

MS,&movespeed
J3, &x_pos, &y_pos, &safe_z 'jog to start position
MZ,&depth 'move bit to cut depth
M4,&x_pos + &length, &y_pos, &depth, &revs 'cut threads
JZ, &safe_z 'move z up

Repeat as needed.
Some of those scary smart indexer math guys (read as Dana) may chime in with a better way, but you can play with this and cut some stuff

[donchandler]

I know it can be done but am asking help. How can a person make threads with a ShopBot? I would imagine you would use a pointed bit but what would the best way to lay out the threads??

What diameter and how many threads per inch? How long is the piece you are trying to thread? Are the threads tapered (pipe threads)? I thread all the time, but I don't use the indexer. I have done it using the indexer with a 60' V bit, but I did not like the quality of the treads.
Let me know what you are trying to do and if the method I use will work for you, I will try and explain it to you.

[jdervin]

Don--

Any chance you'd be willling to share your method regardless of Daryl's answer?

Also, to everyone--

I'd be interested in hearing how people might approach inside threads as well. At one point, I was imagining a project where I would like to have created a threaded hole that could receive a standard broom-handle (the same thread-count/diameter/pitch/etc. used in the ends of many paint roller handles), but wasn't sure how to approach it.

[Gary Campbell]

John...
This has been discussed before, and if I remember correctly, David Buchsbaum was involved and had a great solution using the CC or CP command and the included spiral down parameter. It should be in the archives circa 2008-2009

[beacon14]

Gary your memory is commendable. I used a CP command with a spiral plunge without the bottom pass, and no pull-up at the end.

I ordered a custom-made router bit for both the inside and outside threads. Pics 11-13 in this album (http://s989.photobucket.com/albums/af13/beaconcustom/Table%20for%20Twelve/) show a little bit of the setup.

I drew a section of the joint in CAD to determine starting settings for plunge/rep, diameter, etc, and then fine-tuned it with a little trial and error.

[kubotaman]

Sorry for the long time to reply to you fellas. I was out of state. This question is to everyone. I tried to apply what I thought would work in Aspire. Lets say I want a 2" outside diameter thread on round strock. I thought I could just apply what I wanted in the rotary indexer gadgets included with Aspire. I gave Aspire my length needed, 2" of thread at a pitch of 8TPI. That figure would be a spiral of .25 per rotation. I then let Aspire make the toolpath. Wouldn't that give me the ability to cut the threads? I realize that this would not give me pipe threads but if one knows what a pipe thread's taper is then couldn't you still do the toolpath thru aspire?

[Brady Watson]

Daryl,
You can do this in SB3 using the TI command & filling in the required information.

All the parameters are straight forward, except you'll need to enter in how many times the pattern/spiral will go around the blank. Keep in mind you may have to do some fine tuning in order to get the right root diameter for your threads.

http://i772.photobucket.com/albums/yy8/braidmeister/Indexer_FillinSheet.jpg

Since you want an 8 TPI thread to run, let's say 24" along the length of the blank, you will need to run (8 X 24) or 192 times around the blank to get the thread you need. If you only need 2", then you'd run 16 times around the blank. The indexer tool will let you do tapered threads as well if you change the start or end RADIUS, and run it like that.

Check your dimensions and program as necessary: NPT Threads (http://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html)

-B

[kubotaman]

Brady, that was what I meant to say as far as using Aspire. I haven't really used Partworks or SB3 so that is why I mentioned Aspire. Thank you for the page of threads that was of interest to me that pertains to pipe thread. That was useful to me. Again thank you.

[Brady Watson]

Daryl,
Don't you have a ShopBot?

I don't think you can do threads like this on the indexer with Aspire because it needs to wrap all the way around the blank.

-B

[kubotaman]

Brady you may have a good point. I haven't run a file like what we are talking about but will later today. Yes I do have a Shopbot so I am curious as to the results.

[myxpykalix]

Here is a tutorial from the legacy site that breaks down how to figure pitch/number of starts/spacing in a way so you can figure how to do it manually on their machine but armed with that info you can use the referenced shopbot app brady shows:
http://legacywoodworking.com/technique.cfm?techniqueID=7

[Brady Watson]

Daryl,
SB3 is a free download from ShopBot. If you don't have it because you are running SB2.39 or something, then use it & modify the output file to run on your machine. Aside from you maybe having the indexer in the A channel instead of B, I don't see any reason why it wouldn't work.

This is pretty straightforward...don't over think it.

-B

[kubotaman]

Brady I have the ShopBot 3. I will try it also in Aspire. Doesn't look like it will do any tapering of threads as easy as ShopBot3. It is just that I use Aspire as my first choice of use compared to ShopBot 3. They both have their good points and this may be one of them!

[Brady Watson]

Daryl,
I understand - It's difficult when you can't SEE what is going on with a pretty full 3D preview. Yeah....It's a little bit of a leap of faith, but if you go slow, and try it in a cheap material (like foam or pvc pipe) - you will learn a lot...and probably figure it out.

-B

[kubotaman]

Brady, Just did a file made in Aspire and one made in ShopBot3 and they were exactely the same. Only thing ShopBot3 has over Aspire is the ability to make a tapered thread. I was curious as to how the files ran. Just information someone could use.

[Brady Watson]

Daryl,
Very good - glad that you were able to do it in Aspire. Can you post a screenshot of the 3D with toolpath visible?

Thanks!
-B

[kubotaman]

Brady I have tried for the last half hour to upload the picture of the toolpath. It won't let me, it says it is too large a picture. I don't know what the problem is since I haven't had this problem before. Sorry!

[Brady Watson]

You can join Photobucket, Flickr etc for free. Upload your photos there & then copy the code/link they give you right into the body of the post...

-B