Lathe help

[deema]

I’ve finally found and bought a Cholchester Student lathe. However, I know almost nothing about turning.....so a steep learning curve is ahead of me I believe!

I’d think I’d like to initially start by using carbide tooling to keep away from the sharpening learning curve for high speed steel. So, I’d really appreciate some advise:

Which brand of inserts and insert holders should I buy? Looking on eBay there seems to be cheap Chinese stuff galore as well as some more recognisable brands. What are we’re should I buy?

Can I use any insert (of the same design) on any tool holder, or are they specific for a particular brand?

As a total newly, what would you suggest as a starter tool kit of cutters?

The lathe is the older round top version, but has metric scales and is allegedly a school lathe that has then been used by an enthusiast for the last twenty years. He certainly had a lovely collection cars that he used it to renovate. However, there is a small amount of backlash in the slides, what is an acceptable level of backlash before I know start to worry that I’ve bought a pup?

Is there a more appropriate form I should join to help me with my new toy?

Thanks in advance.

 

[Trevanion]

To be honest, if you're not planning on using it every day you should get the cheapest carbide tooling possible as it will work just fine for general work, if you wanted something a bit nicer you can keep an eye out of eBay and pick up some decent Sandvik or Kennametal gear for not a hell of a lot sometimes. I personally use tool holders that use CCMT type carbides (there's a small CCMT and a Large one) for general turning and a Kennametal A2 part off tool. Don't discount the HSS tooling though as it's very versatile and there isn't much it won't do that carbide will do. This Old Tony has a very good video on the subject:
[youtube]__A2xtLF0AU[/youtube]

Another thing to look at is the tool post of the machine, the old style ones where you shim the tool to the correct height and screw it down are just plain terrible to use. I would suggest something like this toolholder for that size of machine: https://www.chronos.ltd.uk/acatalog/info%5f9511200%2ehtml

Backlash isn't such a big deal as you would first assume, so long as it isn't 1 full turn of the handwheel each time it should be OK. The nice thing about the Colchesters is that it's easy to get new parts for not much, you can buy need feed nuts off eBay if yours are too worn. Could be down to that your tapered gibs need adjusting a little.

Here's a list of sites I deal with for all my Lathe and general metal needs.
https://www.zoro.co.uk/
https://www.cromwell.co.uk/
https://www.rdgtools.co.uk/
https://www.chronos.ltd.uk/
https://www.arceurotrade.co.uk/

 

[deema]

Thanks Trevanion, that’s realky helpful. It came with what I think is a form of quick change tool post, where you remove the whole block which has a cut out at the side to allow it to slip off. However your right it does need the tools to be shimmed first. One of the first things I wanted to do was replace it for the type of post you’ve highlighted. That one looks really nice. Is it a ‘Dickens’ compatible post? (I think that’s the right name as I often see spare too, holders for this type on the bay)

The cross slide has c0.5 or 0.05mm total backlash which is c10 of the smallest divisions of movement. I’m not absolutely sure about the scale at the moment. I can’t detect any lateral movement of the cross slide, but haven’t clocked it. The main traverse also has c10 of the smallest divisions of back lash.

It has a coolant pump and again I’d like to know what and where to buy some coolant.

I’ve got to set it up level and check the alignment of the tail stock. I’ve been looking at the ground alignment rids available from India on eBay. Would you say these are worth the investment, or is there a better source?

 

[Trevanion]

Thanks Trevanion, that’s really helpful.

Least I could do for you helping me out with that switch problem I had . That switch off eBay worked a treat and could run the planer with the belt tight whilst with the old switch the belt had to be slack before it would start.

Is it a ‘Dickens’ compatible post? (I think that’s the right name as I often see spare too, holders for this type on the bay)

It isn't compatible with Dickson holders as far as I know. This tool post has male dovetails on the post and female ones on the holders, with a cam-lock in the post which pushes the tool holder tight against the dovetail. It's a very stout system. If I recall correctly the standard tool holder size for the medium size is a 250-201 which can be picked up fairly cheaply from those China direct sites.

The cross slide has c0.5 or 0.05mm total backlash which is c10 of the smallest divisions of movement. I’m not absolutely sure about the scale at the moment. I can’t detect any lateral movement of the cross slide, but haven’t clocked it. The main traverse also has c10 of the smallest divisions of back lash.

That's pretty good! My lathe has about 1/8th of a turn of backlash. It doesn't really affect the ability to make parts unless it's really bad and you spend more time spinning the handles rather than moving the carriage.

It has a coolant pump and again I’d like to know what and where to buy some coolant.

I go into my local engineering firm to get it by the plastic milk-bottleful, I couldn't tell you what it was called but it was only £5 for the full 4-pint bottle and once Diluted to 1-20 parts by adding the oil to the water rather than vice versa, it filled up my machine completely and filled another couple milk bottles full of it. Make sure to write "Not Milk" on it though, it could fool you as it's white! I haven't had to change out the fluid or top it up yet. Although you might need to clean your coolant tank first from swarf and rust sludge, it's a right horrible dirty job.

Also, get the oils required for your machine to run smoothly as they constantly need topping up. I think Telus 32 and Telus 46 should suffice for most of the machine but it would be worth checking what's proper for it.

I’ve got to set it up level and check the alignment of the tail stock. I’ve been looking at the ground alignment rids available from India on eBay. Would you say these are worth the investment, or is there a better source?

I didn't bother doing this on my machine so I couldn't tell you either way. I know it's sacrilege but at the moment mine just sits roughly level on some wooden bearers. The way I looked at it was that it would be easier to shift in future if it's 2 inches off the ground and they also used lathes on boats and submarines which were hardly level most of the time! I suppose it wouldn't hurt to ask around to borrow an actual alignment bar as I'm sure one delivered from India probably won't be dead straight by the time it gets here.

I buy a lot of silver steel off this company which is straight and precision ground, they might be able to help you out with one: https://www.groundflatstock.com/Shop/Engineering/c/silver-steel/p/silversteel-silver-steel