Assessing lathe wear for purchase

[captainreg]

Hi All

I’m looking to start equipping a model engineering workshop and went to view my first lathe yesterday and would appreciate a bit of advice on assessing wear.

First thing to get out of the way was that yes, unsurprisingly it was a super 7 but that’s a whole other debate :-) My issue was that to my eye it was a very well cared for machine in excellent condition and showed all the signs that it’s just been used for model engineering by one owner over a long period. I ran the carriage along the full length of the bed and there was a very distinct change in feel between two ends. I’m expecting some degree of wear but I have absolutely no idea how to quantify how much is too much by feel alone.

I was hoping someone could give me a steer if I’m worrying about nothing or going about assessing the issue in the wrong way (I don’t yet own measuring equipment to really do anything other than a subjective assessment). What I’m missing is the experience of what a new machine feels like compared to a worn out one and where on that scale it becomes a problem.

Kind Regards
Richard

[simplyloco]

Dec 10, 2019 12:24:53 GMT captainreg said:

Hi All

I’m looking to start equipping a model engineering workshop and went to view my first lathe yesterday and would appreciate a bit of advice on assessing wear.

SNIP
Kind Regards
Richard

Very difficult to assess at long range. However, my 35 year old EMCO Maximat V10P lathe is distinctly stiffer at the last two inches before the headstock, but as I don't go there it makes not one jot of difference to the accuracy of my work. Where are you, how much is the lathe, and do you really want it?
Regards
John

[jackrae]

And you can always get the bed shear faces reground (professionally) if the lathe itself is cheap enough

[rrmrd66]

Hello Richard

This is just my opinion having a factory recon Myford Super 7 and an ancient Harrison M300.

If you have the room (and access) in your workshop look to go for the Harrison M300 (or Colchester equivalent). Myfords are good but no match for a "proper" lathe. You will find the Myford quite limiting in size range especially if you start straying towards larger diameters.

I had my Harrison given a health check by an ex Harrison factory fitter and here are some of his tips.

Get yourself a Dial Test Indicator, known as "clock", (lever type not the plunger) and magnetic base.

Put the lathe in "neutral"if you can.

Remove chuck and check concentricity of the mounting diameter for the chuck,(it might be a conical fitting or a plain counter bore). The spindle should turn easily and quietly.

Replace chuck and repeat on the OD of the chuck. Depends how much of a perfectionist you are but +/- 0.0025" should be good enough. Less than that is good.

Put, say a 3/4" to 1" dia ground bar in chuck. This will not go up the spindle bore of a Myford BTW,(a serous limitation in my view) and check again. If the lathe has had a hard life and the scroll is worn then you may need a new chuck.

Put the clock on saddle carriage and lever arm on lathe bed at zero. Wind saddle down the length of the lathe bed. This checks wear in the lathe bed. You will find more in the area of the chuck as this is where most work is done.The less wear the better, and 0.010" is too much.

If the bar is long enough and has a center bore in the end clamp between chuck and tailstock and repeat above.

You can buy expensive precision ground bars but ordinary bright mild steel bar is good enough to give a preliminary check.

This will get you started.

It really is a question of what you hope to achieve and the level of accuracy you aspire to. Remember if you are building an engine from castings you are only reproducing what a Victorian "blacksmith" was doing.

Apparently steam engines are very forgiving when it comes to super accuracy.

All the best

Malcolm

[coniston]

Hi Richard, I believe the Myford lathes don't have hardened beds, so wear will be present in all but a hardly used machine. My own S7 is pretty badly worn at the headstock end where most work is happening, not surprisingly. But unless you're machining long parallel pieces you should be able to cope with it. Machines with 'Vee' beds for the saddle to slide on are generally hardened so wear will not be so prevalent unless it has had a very hard life. The other thing with a Myford is the versatility and wealth of accessories available either genuine Myford or designed to fit one. Limiting factors of the Myford are well described by Malcolm above. Another consideration to accuracy is to ensure it is levelled properly when installed. In the Myford manual it explains how to do this by turning a bar in the chuck at each end without changing the settings and measuring the difference. Adjust shims under the feet to remove the twist causing any discrepancies.

Hope this helps

Chris D

[goldstar31]

Several issues about Myfords.
Few have hardenned beds but the serisl numbers which help are stamped on the rear shear. I think Myford/RDG Tools gives a record.

There are at least 2 versions. The earliest have a sight glass for lubrication whilst the others are wick fed. Again, the early ones have the'narrow guide' priciple which means that nothing bears against the number 4 shear. The worst case scenario is perhaps as follows.
Usually the worst wear takes place 6 inches from the chuck end of number 1 shear. There should be little wear on the number 2 shear and wear can be compared' bridging' across them.
Inevitably, there will also be some wear on the top of the bed. It can be levelled with blancharding fairly cheaply and the front shear scraped or rather more cost the whole lot can be slideways ground and the wear in the saddle built up with Turcite.

The foregoing is my experience on a very old Mark 1 with the sight glass. I hope that this helps for now or the future.

[captainreg]

Thank you all for the info and advice.

I definitely aspire to something bigger but as a first lathe I think I need to walk before committing to a massive immovable lump! No point in getting a 600kg Colchester and realise that in reality the hobby maybe isn’t for me.

The accuracy requirement of a steam engine in reality is something I was thinking about incorrectly and as an engineer 9-5 I should know better! I’d rather have a finished project to realistic tolerances than a box of perfect parts I’ll never manage complete.

At the end of the day it’s going to come down to the price, when a brand new Warco is almost impossibly cheap in comparison to a 50 year old Myford of unknown provenance! But I figured the Myford would always resell reasonably well.

Kind Regards
Richard

[simplyloco]

My choice would be Seig C4 or Warco WM 180. Modern, accurate, they resell easily  and they have serial numbers that are not in Roman numerals...
John

[glynmar]

I bought a secondhand Axminster SC4 18 months ago and am pretty pleased with it. Doing measuring tests with a dial gauge it’s quite accurate. I didn’t like the backlash and have fitted DRO on the all the axis’s so it is no longer an issue. It also has the mini mill attachment fitted which is OK but a bit lightweight for milling. I paid £1000 for the lathe/mill and £200 for the DRO direct for China so it represents very good value for money. At some point I probably buy a bigger separate milling machine but still keep the lathe.

[goldstar31]

I paid £350 for the lathe- with the silly round DRO's and about £350 for the mill drill. Can't grumble