Shop Floor Talk  

Go Back   Shop Floor Talk > Welding and Metalworking Forums > Machining

 
 
SFT Search:
Reply
 
Thread Tools Display Modes
  #1  
Old 09-22-2023, 06:19 PM
Dr Dean's Avatar
Dr Dean Dr Dean is offline
no bull it's huge!
 
Join Date: Dec 2004
Location: Oakland Ia
Posts: 1,820
Default Making an extruder screw

So I have jumped right into another hair brained idea. My wife wants a patio but as usual I just can't bring myself to do anything normal. So I have been experimenting with recycling plastic grain bags and I've decided that the best way is to extrude it into a mold. I have a piece of 1.75" I'd 1/2" wall pipe and I would like to make the screw to go inside of it. I think I want to use a 1" pitch on the auger flight but my little craftsman lathe only has gears down to 4 tpi. I need some ideas to get the lower pitch, obviously I will be making some parts to make it happen I'm looking for suggestions.
What I have in mind is a .25" thick flight with .75" between them. The center od will start at probably .75" for 12 inches then taper out to 1.25" over 12" then run that size for another 6". I do have a taper attachment so the taper won't be an issue.

Sent from my Pixel 6 using Tapatalk
__________________
The person who said "no guts no glory" is probably dead.
There is no such thing as too much ammo.....the real problem is a target deficency.
Reply With Quote
  #2  
Old 09-22-2023, 08:36 PM
Scotts's Avatar
Scotts Scotts is offline
Stuff, Just stuff
 
Join Date: Dec 2004
Location: Wichita Kansas
Posts: 5,687
Default

That sounds interesting. However, why do you need a screw?
If you are only using one resin and not worried about mixing it with a screw you may be able to inject it just like a syringe, albeit a heavy duty syringe.

If you have an idea of the volume of the part you are making you could design your syringe around that. Do you have a hydraulic press to operate the syringe?

https://youtu.be/cVsRX0jnsqE?si=U3FrO5bpLUE6zyDZ here is an animation of the injection molder with the screw and all. You might be able to make your parts just by heating the tube with a torch and pressing the plastic into a mold.

Here is manual molding machine. https://youtu.be/5AMkaljguJg?si=Dga28-Z-boqyoDA8

You might know all this already and I did not know how to make the screw on your lathe.

Scott
Reply With Quote
  #3  
Old 09-23-2023, 12:20 AM
arizonian's Avatar
arizonian arizonian is offline
Elite Member
 
Join Date: Jul 2007
Location: Tucson, Arizona
Posts: 2,246
Default

What lathe? Quick change gears? Give us a photo of the gear train. Do you have means to cut new gears?

In case you missed it, I added a gear to my gear train to make 11-1/2 TPI by fudging the gear train.
__________________
Bill in sunny Tucson

I believe in gun control.

Gun Control: The ability to consistently hit what you are aiming at.

Weldor by choice, engineer by necessity.
Reply With Quote
  #4  
Old 09-23-2023, 09:35 AM
dubby's Avatar
dubby dubby is offline
Twice the size--half the man
 
Join Date: Apr 2006
Location: Lubbock, TX
Posts: 10,445
Default

I have no idea on how to make the auger either, though I've got a fair bit of experience in hand molding plastics.

I'm not sure whether to ask for more information on what type of parts you're planning to make or just stay outta the way on this one.
__________________
I've always had more time than money.

Wade's Custom Kydex
Reply With Quote
  #5  
Old 09-23-2023, 10:07 AM
midmosandblasting's Avatar
midmosandblasting midmosandblasting is offline
Blast this!
 
Join Date: Oct 2005
Location: Calhoun ,Mo
Posts: 9,104
Default

How are you planning to melt .
Reply With Quote
  #6  
Old 09-23-2023, 02:34 PM
Dr Dean's Avatar
Dr Dean Dr Dean is offline
no bull it's huge!
 
Join Date: Dec 2004
Location: Oakland Ia
Posts: 1,820
Default

Well what I would like to do is make planks, say 1X6X8 foot. I had thought about a piston pump type arrangement, like a concrete pump however heating and making it started to sound like a lot for an experiment, honestly making a screw seemed easier on the surface.
For heat I was planning on a sleeve around the extruder tube with a propane burner.
I've had several thoughts on getting the pitch I want. One is to make a coarse lead screw with coarse half nuts. Another idea would be to chain drive the lead screw off of the part being turned. I'm just tossing some random numbers because I haven't checked the thread pitch on my lead screw. Say it's 10 threads per inch so my gear increase would need to be 1:10. 10 tooth driven with a 100 tooth drive.

Sent from my Pixel 6 using Tapatalk
__________________
The person who said "no guts no glory" is probably dead.
There is no such thing as too much ammo.....the real problem is a target deficency.
Reply With Quote
  #7  
Old 09-23-2023, 02:39 PM
Dr Dean's Avatar
Dr Dean Dr Dean is offline
no bull it's huge!
 
Join Date: Dec 2004
Location: Oakland Ia
Posts: 1,820
Default

BTW I started out bright and early this morning with big intentions. About 10 minutes in I decided to move a mold I had made from 16ga sheet. Well I hadn't deburred it and it got away from me. Seventeen stitches later my right wrist isn't leaking anymore.

Sent from my Pixel 6 using Tapatalk
__________________
The person who said "no guts no glory" is probably dead.
There is no such thing as too much ammo.....the real problem is a target deficency.
Reply With Quote
  #8  
Old 09-23-2023, 04:48 PM
toprecycler's Avatar
toprecycler toprecycler is offline
Administrator
 
Join Date: Jan 2009
Location: Petoskey, Michigan
Posts: 6,908
Default

Ouch. Do your best to stay out of those medical places. Sick people hang around those places.

Arm looks bad, but could have been worse.

Now this project has to continue thru, just because you can’t let it beat you.


Sent from my iPhone using Tapatalk
__________________
Brian

You don't know what you don't know.

"It's what you learn after you know it all that counts." John Wooden
Reply With Quote
  #9  
Old 09-23-2023, 05:17 PM
midmosandblasting's Avatar
midmosandblasting midmosandblasting is offline
Blast this!
 
Join Date: Oct 2005
Location: Calhoun ,Mo
Posts: 9,104
Default

Commercial is about 3 inches between highs of flight . I am guessing lower distance between highs will give better melts .We had a member that worked on injection molding equip .
Reply With Quote
  #10  
Old 09-23-2023, 06:37 PM
arizonian's Avatar
arizonian arizonian is offline
Elite Member
 
Join Date: Jul 2007
Location: Tucson, Arizona
Posts: 2,246
Default

So, 1x6x96 = 576 cubic inches. That's a lot of heating and then cooling before the mold can start the next run. Let's say the density is 0.05lb/in3, that's almost 29 lbs.

Best guess is the lead screw has 8TPI. That lends itself well to different pitches via the gear train. You will need to cut gears that will overdrive the lead screw by a factor of 4 when set up for 4TPI. Not familiar with the Atlas/Craftsman lathe, I take it there is no quick change?

On edit, you will have to make multiple upon multiple passes, that little lathe will not cut a 3/4" wide swath.
__________________
Bill in sunny Tucson

I believe in gun control.

Gun Control: The ability to consistently hit what you are aiming at.

Weldor by choice, engineer by necessity.
Reply With Quote
Reply

Thread Tools
Display Modes

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

Web Search:

All times are GMT -5. The time now is 07:55 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.