Thread cutting on the lathe ??

[4-6-4]

Greetings Chaps I am enjoying this thread. No need to drool over these fancy tool holders. A lump of square HSS in a tool holder is sufficient. Grind more off the right side of the tool as you look down on it so you can come up to a shoulder. Using a thread gauge to get the correct angle. Beginners if possible should always use a thread run out. This is a groove at the end of the thread usually made with a round tool so the half nuts can be disengaged with the tool in clear space.
Next Tip. There are usually a number of positions where you can engage the half nuts. So after you have taken the first 10 thou cut take the tool back to the start and without taking a cut engage the half nut at each possible position taking note if the tool lines up with the first cut. You may only be able to drop in at one particular point. Also at this stage count the number of thread with a rule to make sure that you have set the machine correctly.

The method I use allows you to easily pick up the thread after you have had it out to be resharpened if you chip the point of the tool. Using the top slide in its normal position allows you to pick up the thread easily. If you have the top slide turned to half the angle of the thread it is much more difficult to pick up the thread to continue cutting..

Sorry about running off at the mouth but I can sympathize with a beginners problems. As I said before Come to Melbourne for a weekend and I will set you straight

Yours 4-6-4

[Ueee]

Thanks 4-6-4,
I just use a 1/4" square HSS bit as you say, just looking at the price of carbide puts me off, so i could imagine what these ifanger ones would cost.
I don't use the thread counter on my little lathe as it only came with one gear (metric leadscrew) and i have just gotten used to reversing the machine. I will remember the thread dial trick once the LeBlond is up and running though. I'm keen to cut some threads now just to try the compound set at 0 deg (not 90)

[welder]

Thanks for all the great responses and the offers to actually show me how to thread might take up those offers if I can't figure it out. I ground the tool on the cutter grinder yesterday and apparently it gives great finishes I also forgot I had one of these in my toolbox

[pipeclay]

Werent you able to get suitable advice from where you are doing your apprentership.

[welder]

Short answer NO

[jack620]

... I also forgot I had one of these in my toolbox

Maybe this smilie would have been more appropriate:

[4-6-4]

Greetings chaps. The Answer that no help was forth coming from his work especially when it an apprentice concerned is very poor. If you show interest I was always helped. The Tramways Workshop at Preston machine shop always had 15 apprentices not a huge number but the older men who were attending until retirement were a wealth of information and help if you wanted it.
By the way that is a sexy thread cutting device in the last pic looks as though it has a slight set on it never seen that type before. Yours 4-6-4

[Steamwhisperer]

Greetings chaps. The Answer that no help was forth coming from his work especially when it an apprentice concerned is very poor. If you show interest I was always helped. The Tramways Workshop at Preston machine shop always had 15 apprentices not a huge number but the older men who were attending until retirement were a wealth of information and help if you wanted it.
By the way that is a sexy thread cutting device in the last pic looks as though it has a slight set on it never seen that type before. Yours 4-6-4

HI 4-6-4,
I can assure you that Andre would possibly be the most 'interested' apprentice going around and is not afraid to ask. Maybe the tradesmen are young'ns and aren't sure themselves. Your comment about showing interest to older tradesmen is spot on. They certainly helped me as well. Just look at this forum.
HI Andre,
with the screwcutting tool you found in your toolbox, have a look at the form tool. It should have the thread angle and TPI range (if imperial) stamped on it.

Phil

[welder]

The tool Does have some markings on it but they don't obviously indicate tpi and thread angle. As for work there are 4 people there the oldest chap said feed with the offered some useful advice the younger guy just said plunge cut the thread thencthere was a debate between them about the pros and cons of each method. My tafe teacher was the biggest help I showed him the same photo I showed work and he instantly identified my problem he's great he Even gave me tips on metal scraping and talked to me for about an hour on how to scrap.

[19brendan81]

"I asked my Tafe teacher and he said I had my compound wrong which I did I had it set to 29 on the scale he said I had to set it from 90 so it reads 61 on the scale. he also said we can grind my tools on the cutter grinder."

I just read this thread from page 1 and was about to offer you this advice as my early experiences with thread cutting was precisely the same as yours, and the above was what I was doing wrong. As soon as I corrected the compound angle it all came together.

Hopefully this works for you, im certain its what your problem is from what i have read.

Brendan

[welder]

I'm excited. I have a sharp tool with the right clearance angles some steel to practice on and tommorow I will have a lathe :u

When I was in Mick moyles this afternoon there was a nice old machinist there who told me a very simple calculation to work out the depth of imperial threads I'm sure its not new but I thought it was cool. thread depth = 1280÷tpi÷2

[Vernonv]

thread depth = 1280÷tpi÷2

or simply thread depth = 640/tpi


... but I can't vouch for the validity of the formula.

[jack620]

What grade of steel do you have Andre? This thread inspired me to try making an M16 bolt today. My first attempt was with an unknown grade of steel. The bolt was OK, but the surface of the thread was very jagged. I made very light finishing cuts and used heaps of cutting oil.

Next I made another M16 bolt out of some 1214 steel. I used exactly the same setup and the finish on the threads was very smooth. I didn't even sharpen the bit after making the first bolt. Obviously the type of steel has a big effect on the quality of the finish.

Incidentally, I found the surface was much smoother if I only took 0.05mm deep cuts. Initial cuts were 0.2mm deep.

Chris

[welder]

I was using bms but I now have some random grade of cold rolled steel.

[pipeclay]

Your cuts for a vee thread are very shallow to start with.