Advice on small lathes

[Roger B]

Glad to see you are underway with your new machine     

Proxxon offer the PF230 milling head to fit on the back of your lathe however if you have the space (and money) I would suggest a separate small milling machine. I have a combined lathe and mill which can be a problem when you want to turn a small spacer or mandrel when you are in milling mode.

I would first look for any small ridges or bumps on the taper for the chuck. If there are any carefully remove them with a fine file. Next mark the taper with something (ideally engineers blue but chalk or marker pen will work) and fit it into the socket and turn it round. This should confirm if there is even contact along the length of the taper. If the contact is not even you will need to find or borrow something with a known good MT1 taper to see if the problem is the chuck or the socket.

HSS parting tools are usually better for small lathes as they are sharper than carbide tips. Setting the tool to the correct height is critical. It should be at or just below the centre of the work or it will rub and not cut. Can you post a picture of your parting tool. It is possible it has not been ground correctly. I use HSS parting tools on my PD 150 (one size smaller than yours).

[derekwarner]

nat......a few observations

1. your PD 250E is obviously near new......& has a No2? Morse taper in the tail-stock....drilling any hole with a clean HSS drill bit to the capacity of the chuck [10mm?] should not cause any issue between the tailstock/chuck & the workpiece

If you are experiencing rotational chatter of the chuck arbour. would indicate contamination in the Morse taper M&F components.....after this happens, take the chuck+arbour from the tailstock.......you may well find a small shiny point on the OD of the arbour that is causing this........it is totally acceptable to remove this shiny spot by 1200 W+D paper as needed..... reinstall & repeat exercise

The Morse taper is designed to hold, never use Loctite 

Some 50 years ago, a Tradesman machinist taught the apprentice that if a drill arbour slipped in the tailstock, ....take a single leaf of roll your own cigarette tobacco paper & glue it to the arbour [No4 Morse] & that sure eliminated the rotational issue

2. the same Tradesman machinist also taught   me never to leave the headstock chuck key in a lathe

3. I agree with Roger, that HSS tool bits are absolutely preferable for 9/10 tasks in model engineering machining tasks

Derek

 

[nats]

Glad to see you are underway with your new machine     

I'm trying, in a small appartement it's always a challenge to do that at respectful hour (and to clean the mess after)

Proxxon offer the PF230 milling head to fit on the back of your lathe however if you have the space (and money) I would suggest a separate small milling machine. I have a combined lathe and mill which can be a problem when you want to turn a small spacer or mandrel when you are in milling mode.

I saw that and it's on my buy list in the future, a fully separated FF230 with chuck support etc... I don't want the "addon" because the space on this lathe is really small.
For cost reason I can't buy it soon so I was thinking buying those sort of Z carriage you can put on a lathe to make small milling work:
http://www.deansphotographica.com/machining/projects/millingattachment.html

Something like that.

I would first look for any small ridges or bumps on the taper for the chuck. If there are any carefully remove them with a fine file. Next mark the taper with something (ideally engineers blue but chalk or marker pen will work) and fit it into the socket and turn it round. This should confirm if there is even contact along the length of the taper. If the contact is not even you will need to find or borrow something with a known good MT1 taper to see if the problem is the chuck or the socket.

I'll try do that at first, but I always took care of not having dust or chips in the chuck cone. What puzzle me is that I managed to do a lot of holes with before but never tried anything over 6mm.
My other clue the drill bit is not the cause is that I managed to drill the hole in a low cost drill press (parkside from lidl for those who know )

HSS parting tools are usually better for small lathes as they are sharper than carbide tips. Setting the tool to the correct height is critical. It should be at or just below the centre of the work or it will rub and not cut. Can you post a picture of your parting tool. It is possible it has not been ground correctly. I use HSS parting tools on my PD 150 (one size smaller than yours).

I'll post a picture this evening but it's a proxxon HSS parting tool and I tried to go through a 14mm diameter soft steel bar. (the same bar is ultra easy to lathe). I can feel it force
a lot and the noise is awful (with a lot of vibration) so I didn't want to push more. I took the time to adjust the height using sheet of paper and to align at pi/2.

nat......a few observations

1. your PD 250E is obviously near new......& has a No2? Morse taper in the tail-stock....drilling any hole with a clean HSS drill bit to the capacity of the chuck [10mm?] should not cause any issue between the tailstock/chuck & the workpiece

If you are experiencing rotational chatter of the chuck arbour. would indicate contamination in the Morse taper M&F components.....after this happens, take the chuck+arbour from the tailstock.......you may well find a small shiny point on the OD of the arbour that is causing this........it is totally acceptable to remove this shiny spot by 1200 W+D paper as needed..... reinstall & repeat exercise

The Morse taper is designed to hold, never use Loctite 

Some 50 years ago, a Tradesman machinist taught the apprentice that if a drill arbour slipped in the tailstock, ....take a single leaf of roll your own cigarette tobacco paper & glue it to the arbour [No4 Morse] & that sure eliminated the rotational issue

2. the same Tradesman machinist also taught   me never to leave the headstock chuck key in a lathe

3. I agree with Roger, that HSS tool bits are absolutely preferable for 9/10 tasks in model engineering machining tasks

Derek

Hello derek, not sure if it's what you mean but the Headstock is a M2 cone and the tail stock is a M1. It's really a small lathe I'll try what Roger and you advised for the drill chuck and let you know the results, sadly I don't smoke anymore and don't plan to start again I have a milling machine to buy !

The parting tool is the one on this page on the right, reference: NO 24 530 https://www.proxxon.com/en/micromot/24002.php all the other tool of the set goes pretty well through the same steel so indeed it doesn't seem to be HSS problem.

Thanks a lot for your kindness and answers

[Roger B]

There are a number of vertical slides available here:

https://www.rcm-machines.com/en/vertical-slide

Maybe one is suitable

[nats]

Thanks Roger,
I bookmarked the website, I'll check if I can make an adapter for the pd250e.

[Roger B]

I normally use the blade type parting tools but I have a 6mm Proxxon tool that came with the set I got with my FD150. I set this up in my Hobbymat which is similar in size to your PD250. I needed to part off some 15mm free cutting steel for the starter coupling for my two cylinder engine. It is set about 0.5mm below centre and running at 500 rpm. You need to be confident and keep the feed rate up otherwise it will just rub.

<a href="https://www.youtube.com/watch?v=gA7oyYUDNsk" target="_blank">http://www.youtube.com/watch?v=gA7oyYUDNsk</a>

[sorveltaja]

One thing about using vertical slide on the cross slide of 250E. If it has a cross slide made of aluminum, as my older PD 210 have, it just isn't rigid enough for milling metal, unless you take very light cuts.

[nats]

Thanks for the video Roger, for me it confirms I do something wrong because I tried a steady feed and the noise is really horrible in you case it doesn't "scream" and vibrate like hell.

I'll give it a try this friday or during the week end and film it maybe someone will spot an obvious mistake

EDIT: I forgot to say the chip are not like yours with clean length, it makes million of tiny small hair it's really weird.

One thing about using vertical slide on the cross slide of 250E. If it has a cross slide made of aluminum, as my older PD 210 have, it just isn't rigid enough for milling metal, unless you take very light cuts.

I was thinking using that for really light cut and really small work but I'll try to get a FF230 asap. The only one I could get fast would be a MF70 but it seems to be really lite for a mill.

[Roger B]

I have an MF70. It is certainly limited but it is useable. I have machined some rocker arms from 6mm square C45k (key steel), machined the cavities in some 20mm diameter pistons and cut 1.4, 2 and 3mm keyways in various shafts. It works well with the Proxxon milling cutters. I have not tried with anything else.

[nats]

Hello Roger,
I'm impressed because it's really a small machine !
Anyway I think I'll try to keep money to have something like FF230. It'll certainly give me a little more freedom.

I'll try to do the parting video today or tomorrow

[nats]

Hello,
I don't know if mechanic designer have the same expression but developers have "The Rubber Ducky" effect.

I promised to post a video of what doesn't go well when trying to part off piece on my lathe but it didn't go as expected !

First it's an (unknown but probably S300pb) mild still bar with a radius of 7mm, so I expect a base cutting speed of 20m/min, giving me a 500RPM setting.

I then marked the center of the piece to align the tool (I take way more care about that parameter than before) I estimate my alignment at less than 0.3mm.

I selected the second speed in the gearbox, going from 400 to 1600 RPM (electronic variator, you'll see it'll cause troubles )

Link to the video 1 : <a href="https://www.youtube.com/watch?v=0qPfyUKGd7Q" target="_blank">http://www.youtube.com/watch?v=0qPfyUKGd7Q</a>

First reaction: "Ohhh god it's working !" Yeah, I'm the most confused here I think your comments made me do everything correctly taking time to carefully check !
Seeing the stalling motor it's clear the torque is not here, it's not a monster beast but it's a 150W motor ! So, let's sacrifice few RPM and go back to first speed in the gearbox.
It'll put us at 400RPM but with way more torque (don't forget electronic variator work by lowering the average current provided to the motor, usually by hashing current).

Link to the video 2 : <a href="https://www.youtube.com/watch?v=Tc3jjeVZAvk" target="_blank">http://www.youtube.com/watch?v=Tc3jjeVZAvk</a>

So this try didn't go as expected at all ! It worked

Thanks you all for advices ! Special thanks to Roger who always take a lot of time to answer me

[Roger B]

Excellent  Unfortunately I can't see the videos but it obviously worked. I think that the first time the tool was just above centre height and was rubbing.

[nats]

Hello Roger,
Is there any problem with youtube videos ? I don't know how to set things correctly I used youtube really few times before.

[Roger B]

There does seem to be a problem with some browsers if you use the forum's embeding function. I just paste the YouTube URL.

[nats]

Oky I removed the youtube embedding and just pasted the link, it should be better I think.