Project of the Month built by mirek111

Help Support Home Model Engine Machinist by donating using the link above or becoming a Supporting Member.
Home Model Engine Machinist > The Tools and Tips > Tips and Tricks > Threading ?s

Reply
 
Thread Tools
Old 12-01-2017, 06:09 AM   #21
Naiveambition
 
Join Date: May 2012
Posts: 261
Liked 54 Times on 37 Posts
Likes Given: 21

Default Threading ?s

Adding some closure to this thread.

I was able to accomplish my threads but not without some complications and discoverys.
For this mission I switched to alum. The male thread went as planned but the female still presented issues. 1st being I found my leadscrew clamp was busted and with cuts under.01 it was fine but any more it would slip out of sync and kick the gearbox out of gear losing my place. So after fabing up another solved my issues there. The second issue was most likely cutter geometry. Was not cutting nice clean chips, more of a tear style chip. Under power it was enough to stop my little 7x10 so had to resort to hand turning the lathe and finally made it thru.

I chose 20 tpi and cut till I had one full turn on the dial or .1 I think.. Now granted I made my own 60* guage for setting the tool and prob made mistake of using small top rake. So not perfect but worked in the end will need some more practice but at least the steps are down and work on the finer points.

Here's a pic of my parts The iPad cam has no definition so they do look better than the photo.


Attached Thumbnails
image.jpeg  
Naiveambition is offline  
 
Reply With Quote
Old 12-04-2017, 03:04 PM   #22
Sansspaceship
 
Join Date: Jan 2017
Location: Australia
Posts: 37
Liked 8 Times on 8 Posts
Likes Given: 11

Default

Glad you had some success, will leave others to comment on cutting geometry as grinding cutting tools isn’t one of my strong areas. But something is definetly wrong if it gouging and not cutting, my initial thought would be too deep a cut, without enough horse power (as alu can be gummy) but won’t comment past that as am only guessing without more details.

Anyway good luck with you project, thanks for the update.

Cheers,
Adrian


Sansspaceship is offline  
 
Reply With Quote
Old 12-04-2017, 05:08 PM   #23
BaronJ
Grumpy Old Git.
 
BaronJ's Avatar
 
Join Date: Dec 2013
Location: Yorkshire, UK
Posts: 632
Liked 232 Times on 195 Posts
Likes Given: 91

Default

Hi, From looking at your picture of the threads in the ring, make sure that the tool has enough clearance under the front and side edges. It looks as if it is rubbing and tearing the thread. I've had this problem with home ground tool bits. The problem gets worse with smaller holes. I have started to buy small carbide threading bits, which gets around this problem nicely. You still have to watch the hole size though.

HTH.
__________________
Regards:
Baron.
BaronJ is offline  
 
Reply With Quote
Old 12-04-2017, 09:33 PM   #24
JCSteam
 
Join Date: Nov 2016
Location: Darlington
Posts: 357
Liked 61 Times on 55 Posts
Likes Given: 343

Default

Just throwing this out there, with regards to the comment of Ali been gummy, have you tried cutting Ali with WD40. It stops the Ali cold welding itself to the tip, which may be another cause of the dragging that you've experience. For the sake of a couple of quid for a tin may be worth a try.
?? It did wonders on a part that I was turning, plus the chips just rolled off the cutting tool.

I by no means profess to be an expert, this is just my observations from my own work.
JCSteam is offline  
 
Reply With Quote
Old 12-06-2017, 01:58 PM   #25
Sansspaceship
 
Join Date: Jan 2017
Location: Australia
Posts: 37
Liked 8 Times on 8 Posts
Likes Given: 11

Default

Quote:
Originally Posted by JCSteam View Post
Just throwing this out there, with regards to the comment of Ali been gummy, have you tried cutting Ali with WD40. It stops the Ali cold welding itself to the tip, which may be another cause of the dragging that you've experience. For the sake of a couple of quid for a tin may be worth a try.
?? It did wonders on a part that I was turning, plus the chips just rolled off the cutting tool.

I by no means profess to be an expert, this is just my observations from my own work.
I might have added a bit of confusion by bringing up the gummy alu comment. To clarify I was just trying to read between the lines with the OP comment that he wasn’t getting good chips and it was more tearing which to me might have appeared gummy.

But you point is extremely valid though, when I first started with alu I used wd40 and it works great. Now I use a fog buster as just run it generally set and forget after program proofing on the mill which is where I cut most of my alu, but yes coolant would be recommended when starting out. Although i have had quite a bit for success roughing dry.

The other thought I had was if it wasn’t any of the culprits that have been mentioned by any of the previous posts it could be non heat tread alu, which can be a bear to cut and might explain the tearing, in my experience you want T3 or T6 (common) alu in a 2011, 6061 or 7075.

I too am no expert, but always interested and keen to learn about cause and effect of stuff like cutters and material.

Cheers,
Adrian
Sansspaceship is offline  
 
Reply With Quote
Old 12-06-2017, 02:46 PM   #26
DJP
 
Join Date: Dec 2012
Posts: 257
Liked 76 Times on 64 Posts

Default

I'm sure that there are many cutting fluids available but if you want a 'home brew' try one part kerosene, one part Varsol and one part Automatic Transmission fluid.
DJP is offline  
gggGary Likes This 
Reply With Quote
Old 12-06-2017, 03:50 PM   #27
mcostello
Member
 
Join Date: Sep 2011
Location: Lancaster,Ohio
Posts: 271
Liked 34 Times on 31 Posts
Likes Given: 9

Default

My experience is that any kind of light oil will work, penetrating oil bought at garage sales for a pittance works best as it soothes My wallet at the same time.
__________________
Lancaster, Ohio USA
mcostello is offline  
 
Reply With Quote
Old 12-21-2017, 04:09 AM   #28
rlukens
HMEM_SUPPORTER.png
 
rlukens's Avatar
 
Join Date: Feb 2010
Location: Sarasota
Posts: 82
Liked 42 Times on 17 Posts
Likes Given: 28

Default

It's an absolute must to have the compound rest set at 29 degrees. Make all your advancements with it, not the cross slide. Otherwise your plunging the cutter straight ahead and cutting on both sides. For your last pass, maybe move in on the cross slide a thou or two to clean up both sides of the "v".
rlukens is offline  
gggGary Likes This 
Reply With Quote
Old 12-21-2017, 06:15 AM   #29
Cogsy
 
Cogsy's Avatar
 
Join Date: Jul 2012
Location: Perth, Western Australia
Posts: 1,937
Liked 530 Times on 407 Posts
Likes Given: 529

Default

Why is it 29 and not 30 degrees for a 60 degree thread? I've always wondered this, every time I see the 29 degree figure quoted. I've never tested it myself, having only every cut smallish threads on the lathe and never having an issue with plunging straight in, but it would satisfy my curiosity to know.
__________________
Al.
______________________
I'd like to be a perfectionist, but I lack the patience...not to mention the skill...
Cogsy is offline  
gggGary Likes This 
Reply With Quote
Old 12-21-2017, 09:50 AM   #30
BaronJ
Grumpy Old Git.
 
BaronJ's Avatar
 
Join Date: Dec 2013
Location: Yorkshire, UK
Posts: 632
Liked 232 Times on 195 Posts
Likes Given: 91

Default

Hi Guys,

This controversy over 29-30 degrees and the insistence that this must be, verses plunging straight in, only serves to confuse and confound, newbies in particular. I would suggest that most of us would only cut relativity fine threads, say more than ten or twelve TPI, so plunging in is not a big issue, and I admit that this is exactly what I do !

For large threads cutting on the forward face, which is what happens when using a 29 degree top slide angle does, lowers the cutting forces because it creates back edge clearance. Doing Acme and square threads is an altogether more complicated proposition.

JM2PW.


__________________
Regards:
Baron.
BaronJ is offline  
goldstar31 Likes This 
Reply With Quote
Reply


Thread Tools

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Threading Rod John General Engine Discussion 5 01-23-2015 03:43 PM
Threading help techonehundred Machine Modifications 7 10-11-2010 12:00 AM
Threading Bits Stan Tools 35 02-05-2009 11:36 AM
threading Loose nut General Engine Discussion 44 01-29-2009 07:26 PM
Threading Oldmechthings Tips and Tricks 0 01-21-2008 03:17 AM



Newest Threads






- Top - Member List