[Newbie] How To Adjust Tool Height On A Lathe?

Hi I'm a newby to this forum, and not the world's most experienced machinist either, but my day job as a design engineer (IC engines) brings me into close contact with many highly skilled members of the UK's machining community and they have all told me that rigidity is king. Any looseness or flexibility brings poor surface finish and chatter etc. Heavy machines with rigid tooling seem to be the way to go - so shims are good (lots of area in contact therefore high stiffness, although a bit of a pain; as mentioned elsewhere getting it spot on centre height is not so important on larger jobs - it IS important for facing to centre or on very small components. Keep on with that 4-way and get clever with the shimming.......
 
Not to hi-jack a thead, but the info here is like manna from heaven to me, but I must have a wrong combination somewhere. I have a 14 x 40 Harbor Freight, new (10 years ago when I was still working). I have to confess that all my tooling came from Ebay and Craigslist. What is wrong is that trying to use both the 4 way, and the Lantern and Armstrong, all my tool holders have their square holes pointing up hill. This angle screws up trying to get all my ready ground HS cutting bits to line up with the c/l of the work. The clamping part of my tool holders measure about 1 1/8 by 1/2" . Everything would work perfect if the square hole was parallel with the c/l of the tool holders, but I don't seem to get anything but uphill square holes. Do straight hole tool holders exist? And if so, what words do I look for when buying tool holders to get the straight square hole instead of these things that are plaguing me.
 
The lamppost-style holder tends to angle the bit like that, so you wind up having to grind the cutters to work with that angle...

But you also mention you have a 4-way [which should look like the image in post #1 of this thread], and unless something is very wrong or very different with your lathe, it holds your cutting tools horizontal, you just need to shim them to the right height.

thinking about it, you may be trying to put the tool holder that is used with your lamppost-style holder in your 4-way. don't do that. you put the cutting tool directly in the 4-way, as shown in post #1 [only with shims as needed underneath the tool to get it to the proper height].
 
Threading on the 4 way takes some getting used to! I have a brazed 60` carbide tool that I think is intended for threading, but it is set "square" and has to cut both sides of the groove as opposed to the lantern post on the cross-slide set at 29`. What am I missing?

Ray
 
Ray,
Do you mean the top slide (compound) is set at 29 deg. ?
Your 4 way is likely indexed, so a detent will locate the tool post at 90 deg. intervals, with each being square to the compound. However the detent should be spring loaded so that it can be pushed below the surface. In that case ignore the detent. With the compound set at 29.5 deg from perpendicular, turn the 4 way post square to the spindle axis and tighten it down. That way the thread tool will be 90 deg to the work and you can use the compound to feed.
 
Tozguy said:
Ray,
Do you mean the top slide (compound) is set at 29 deg. ?
Your 4 way is likely indexed, so a detent will locate the tool post at 90 deg. intervals, with each being square to the compound. However the detent should be spring loaded so that it can be pushed below the surface. In that case ignore the detent. With the compound set at 29.5 deg from perpendicular, turn the 4 way post square to the spindle axis and tighten it down. That way the thread tool will be 90 deg to the work and you can use the compound to feed.
Click to expand...

Remember to use a "fish tail" gauge to align the 60 degree cutting tool.
 
dave_r_1 said:
The lamppost-style holder tends to angle the bit like that, so you wind up having to grind the cutters to work with that angle...

But you also mention you have a 4-way [which should look like the image in post #1 of this thread], and unless something is very wrong or very different with your lathe, it holds your cutting tools horizontal, you just need to shim them to the right height.

thinking about it, you may be trying to put the tool holder that is used with your lamppost-style holder in your 4-way. don't do that. you put the cutting tool directly in the 4-way, as shown in post #1 [only with shims as needed underneath the tool to get it to the proper height].
Click to expand...


You did great forensics here. Putting a tool holder into the four way is exactly what I was doing. Now, I have to get some chunkier cutting tools, as most of mine are small 1/4" - 3/8" - and such. I never said that I knew what I was doing.
 
dave_r_1 said:
given that this is so important, that the default for a lathe is "we got nothing, figure something out yourself" seems pretty lame. I would have expected at least a small fine-tuning adjustment.
Click to expand...

If you think the four way tool post is difficult, you might have had to start with a rocker/lantern tool post. The instructions that come with that are "wiggle until it cuts well, tighten well then readjust."
 
My very first post to this forum guys. I was kind of hoping to find a design for some sort of double wedge adjustable height device for four-way post, but it looks like it is shims or shims. I am long retired now, and use the machinery at the local Menz Shed. This is the metal lathe we have

https://www.machineryhouse.co.nz/L141

It came with a set of tools which all have the same height, so it shouldn't be a big deal. We also have a small mill drill, so I could machine a one piece shim. The only problem being to measure its thickness when four or five assorted thinner shims are uncompressed. Put them in a vice and measure as close to the jaws as possible would do it. Another problem is that I did do this once before, but one of the shed members helpfully tidied the one piece shim into the scrap bin. Perhaps the next one will go into my tool box.
 
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