Help setting up Clarke 500m

Hi to anyone who can help

I'm just going through checking and attempting to set up my used clarke 500m lathe. I have checked the back lash of the feed screws and this is what I have found - saddle feed 1.1mm, cross slide 1.6mm and compound slide 0.7mm. Do these need/can these be adjusted and if so how would I do so?

Also I turned down a piece of 25mm mild steel bar to approx 20mm to check any taper in the cut and within a 25mm length of cut the diameter of the cut goes from 19.96mm at one end to 20.29mm at the other end of the cut, so there is a taper to the cut. Any ideas if this can be adjusted and if so how?

Sorry for my lack of correct terminology, I'm sure I will get there in time 🙄

Thanks Stu

Hi Stuart

I wouldn't worry too much about backlash as long as you always approach from the same direction i.e. wind back further than required then back in again to add more cut.

Removing twist, or 'levelling' the lathe, has been the subject of many postings and a few disagreements so try entering the word "levelling" in the box at the top of the posting.

Rob

Thanks Rob, will do!

I just noticed the tapered cut seems to happen when using the compound slide for the cut, when using the saddle feed for the cut it seems to be ok, no taper!

So it would seem you do not have the compound set square to the chuck face. Lots of vids on you tube showing this being done. Blondiehacks has done a few.

So with your questions do we assume you ended up buying the used model from ebay.

If so, hope you are happy with it.

Steve.

Thanks Steve, I'll check youtube out. I have watched a few of blondiehacks videos 👍

Yes I bought the one on ebay. It was just up the road from me so went and had a look. The seller was really helpful. He has just upgraded to a Warco BH600? which looks very nice but too big for my workshop. I'm very pleased with it for the money, it came with quite a few extras too which is good, a QCTP which I'm really happy with. The lack of the half nut might bug me in time but as I have nothing to compare it to because it is my first lathe, I am happy to keep wind the saddle feed out of the way for now. I have done some turning and facing so far, really want to try screw cutting next.

Any one know a good place to get thread cutting info online, ie turning diameters for each thread size etc? I'm sure I came accross a refence guide somewhere but can't remember where now!

Stuart you could make it a project to build a powered screw feed.

Steve.

It has a powered screw feed Steve, its just it doesn't have a half nut so I can't release the saddle to slide it up the bed out of the way if I want to. No big deal though

Without backlash it would be impossible to move one part relative to another, so must allow for the backlash.

So if you put on a cut of 0.02 mm but overshoot to 0.025, all is not lost.

Withdraw the tool by 1.00 mm. Advance to Zero. Having taken out backlash, you wind in a further 0.02 to where you want to be.

Without taking out the backlash, accurate, or consistent results are impossible.

As a newbie you will learn a lot from books on model engineering.

"The Amateur's Lathe" by L H Sparey..

Neil Wyatt and Dave Fenner have each written books on the mini lathe.

Ian Bradley's "The Amateur's Workshop" covers general techniques

A set of Zeus charts is useful, for many things, plus Tubal Cain's "Model Engineers Handbook " a frequently consulted reference book, on many things.

The mini lathe is a hobby machine designed and built to balance cost versus accuracy and durability.

It lacks the power, accuracy or features of an Industrial Tool Room lathe, or costs as much!

Similar, if not identical machines are available from suppliers specific to the model engineering trade, such as Arc EuroTrade, Chester, Warco, Amadeal, or SPG - to name a few. These are more likely to be able give advice, as well as many on here, than Machine Mart, where knowledge may well vary from branch to branch.

The above suppliers may provide advice and help even if they did not supply the machine.

Where are you located?

Find a model engineering club local to you, and join. Again, advice, help and, Covid permitting, even face to face demonstration, may be possible.

Within its limitations, the mini lathe is capable of good work. Careful adjustment and skill can produce outstanding results.

Do not expect a 3 jaw chuck to hold anything without some run out (eccentricity ) There are very few 3 jaw chucks without run out, Many in good condition ( even brand new   may yet show run out of the order of 0.10 mm A worn or damaged chuck may be even worse, I know of one very old chuck showing nearly 1 mm run out.

Diameters that will,be concentric to each other, as long as they are cut without disturbing anything between cuts.

The taper that you found could be from a variety of things.

1 ) How far was the material into the chuck jaws? For what you are checking, it needs to be gripped by the full length of the jaws. This assumes that the jaws are clean, both where they grip the workpiece, and where they touch the scroll inside the chuck.

2 ) Is the chuck clamped accurately to the flange on the mandrel? The flange and the register on the back of the chuck must be clean, and free from any burrs. If the chuck is misaligned, you will have problems.

3 ) Are the bearings in the Headstock worn or lost their preload? If YES to either of these questions, as a newbie, this is not work that you should undertake without finding out the correct way to check and then rectify the problem.

For this you really need expert attention.

4 ) Were you trying to reduce from 25 to 20 mm in one cut? 2.5 mm in one cut is heavy work. (My handbook says that 0.010" - 0.0025 mm is a roughing cut, although many take far deeper cuts without damage) Lacking the handbook, get one.

For your checks, a cut of 0.05 mm might be more suitable, since it will cause smaller deflections in the machine. Also, your feed rate needs to be slow. Forcing the tool will cause deflections.

Using changewheels and Leadscrew for the feed, a 20:80/20:80 train should produce a feed rate of 0.0937 mm per rev.

5 ) Is the cutting tool sharp? Don't expect good results from blunt / chipped tools.

6 ) Is the tool mounted with the cutting edge is on the centre line of the Headstock?

Quick check; face across the end of a short piece held firmly in the chuck. Off centre the tool will leave a pip near the centre of the work.

A tool above centre will rub rather than cutting properly. A tool, below centre will have the wrong effective angles to cut properly.

Both will need extra pressure to cut, if at all..

7 ) The gibs on the Cross Slide may be slack, allowing movement. Until this is minimised, consistent results are unlikely. The saddle should be located by the Vee bedway, but if there is vertical movement accuracy will be impaired, so that is another adjustment to optimise.

With a second hand machine, you cannot be certain what use / abuse / misadjustment has taken place.

(I bought a secondhand lawnmower. Worked far better once the blade had been fitted the right way up! )

Hence the machine needs to checked over, and excess play removed.

8 ) If you were turning between centres, one of the centres could be "out" and need cleaning up, or the Tailstock could be misaligned.

Easy to rectify, but needs measuring equipment to do as accurately as possible,.

9  Disaster scenario, AFTER you have checked all the foregoing, it is possible, but unlikely that the Headstock is out of line with the bed. Again extra knowledge and measuring equipment is needed to confirm and correct it.

Sorry to ramble on on such length, trying to cover as many options as possible.

Howard

In answer to some of your questions......

The material was a good 2" in to the chuck although has a bit of light surface rust (may be that) it was just a piece of bright steel I had lying around

By using a DTI as far as I can tell the chuck is aligned correctly.

The headstock bearings are new and seem to be correctly adjusted (tapered roller type)

I was taking 0.5mm per cut, feeding slowly by hand with a brand new tool which cut very well, no effort required, nice clean chips etc. I did try a 1mm cut which it also coped with very well

I centrered the tool using the feeler gauge between the blade tip and the material method which seems to work fine

I did notice when using the Cross slide to feed the cutter along the material if I did wind too aggressively the QCTP holder seemed to almost jump a little!? One question I have ref the QCTP holders, what is the nut on the top of the height adjuster for? I tried winding it all the way down but it doesn't seem to do anything ie, doesn't seem to lock the height adjuster??

I wasn't turning between centres and had approx 50mm of material protruding from the chuck

I think as the saddle feed seems to cut without taper suggests the headstock is aligned with the bed and the problem lies with the Cross feed alignment. I did have to adjust the gib strip on this so may have adjusted unevenly?

I will have another play with it tomorrow. Overall I am very pleased with the machine, I'm just trying to follow peoples advice and get it set up correctly

Thanks again

Stu

Stuart post a picture of the adjuster you mentioned on the QCTP. I have one & the adjustment is quite easy to do, to get the cutter to be central to the workpiece.

Steve.

Its the black nut on the top of the adjuster I'm not sure about?

This is the tool post

The compound slide can be at any angle - it won’t make any difference to taper - as long as the carriage is driven for the cut. One would only set the compound to cut parallel (if needed), after success with the carriage!

The chuck run-out should not affect taper - parts are purposely off-set in a 4 jaw independent chuck at times.

The final cut should be less than 0.5mm. Roughing cuts are never needed to be accurate ones. Power feeding is always better for a newbie, if available. As the surface finish will be so much easier to get it uniform. A quick polish with emery strip may provide a different taper than found even now.

Cross slide should ideally be tightened down for longitudinal cuts. Cutting in the reverse direction (at the same setting) may indicate sloppiness in the gib adjustment.

These lathes have a flat bed, so no bed V-way.

Your next check is to cut with tailstock support. A much longer bar (just test with cuts at the ends - so a bar like a dumbell. That will need the tailstock adjusting to provide no difference at either end. Then you are ready to get machining!🙂

Thanks, so are you saying I should be using the saddle feed for parallel turning anyway and not the compound?

I watched a YouTube video by blondehacks for checking tailstock with a long bar, turning a section either end and then measuring any difference in diameter, I guess this is the method you are suggesting?

Many thanks

Stu 😊

Stuart these are different to mine. Someone will advise soon, as many have that type.

Steve.

OK, I have sussed it. The black square headed bolt that screw in to the top of the height adjuster IS to lock the adjuster in to place. But I guess because of where the tool post sits on my carriage, the locking bolts screw all the way in before they lock off the adjuster. I need slightly longer locking bolts to work.

Hopefully a search for longer square headed bolts, m8 x 35mm will bring up some options

Stuart

Remove square headed bolt from the adjuster. Drop either a ball bearing or a very short length of rod into the hole. Replace square headed bolt

Brian

Great idea, thanks Brian

Stuart,

Re the crossslide, may I suggest you take it off to gice the slideways a good clean, to do this loosen the Gib strip screws and the wind the cross slide to the rear of the bed until it stopsthen the slide will move easily off the lathe, be aware the crossslide nut may drop out from the underside of the slide, its a good fit but maybe loose, its not fixed and allowed to float, give all of the parts a very good clean including the Gib strip. Give everything a good dose of oil and reassemble but before you do screw the cross slide nut onto the thread and check for slop, there is a small screw to close the thread and reduce the play, this will reduce the backlash. the reason I suggest this is the slide way does not have a lot of protection from swarf and some may get in to the ways.

Martin P

Thanks Martin. I have just been taking apart the Cross slide as you suggested and in doing so realised I can adjust the angle of the slide, Doh!..... Getting to know the machine slowly 🙄

Ref the cross slide nut, it appears to be fixed to the slide base, most likely from underneath but I can't see a screw for adjusting back lash?