Thread: Taking measurements

Generally speaking the tail stock is made higher to compensate for wear.So as the tailstock wears out,it gets closer to center height rather than be lower than center. Also I am in Newtown during the week so could come say hello not that I will be much help

Thanks Welder, I have read this but I was under the assumption it should only be around 0.025mm or so. btw in the small booklet that came with the lathe are the technical measurements in decimal of inches or mm as it doesn't state which unit?

Originally Posted by Maxi77

... I have read this but I was under the assumption it should only be around 0.025mm or so.

This is one of those "yes and no" questions.
The numbers quoted for machine tool standards (sometime called Schlesinger standards) were devised back around the 1920's (from memory) and were for industrial machine tools. Those standards are not mandatory but there is a general expectation that they would apply. It has been observed here and elsewhere that at the cheaper end of the market (machines more likely to be bought by hobbyists like us) that the interpretation and measurement of machine geometry is a little more elastic than would be expected.

The deviations you are seeing can be fixed but it is not a simple job (the go-to book is one called "Machine tool reconditioning" by Connelly). Depending on the faults present it could take 100's of hours. At the end of the day you will still have a HM-46 and an AL-960b, which is why some of us spend the time on resusitating old industrial iron instead.

It is frustrating to know that something is not what it should be (been there, done that). Whether you should try to fix the issues is a personal choice, depending on time, money and what you plan to do with the machines. 0.08mm is still a small number (for comparison my lathe has a dip due to wear in the bed of a little under 0.2mm), so it could be acceptable for most jobs and as Welder says it is designed for wearing in, so in a few years time it will be better!

Michael

Originally Posted by Maxi77

Hi Guys,
After a few months using my al-960b and HM-46 I am staring to get a feel for them. I figured now that they have been bed in so to speak it was time to get to know them more intimatley and a good opportunity to set them up and take readings of allignments. It has given me time to gain some knowlegde and tackle things I wasn't so comfortable with at the start.

In regards to the lathe I have started taking readings of headstock to tailstock allignment using a mt3 test bar. I have the chuck off and fitted the mt5 to mt3 adaptor and deadcenter. I have got the horizontal allignment within 0.02 mm however the vetical allignment is approx 0.06-0.08mm rising toward the tailstock with the tailstock fully extended. I have ajusted the tail stock mandrel to within 0.01mm on the vertical.
I have the magbase on the cross slide and am turning the carriage wheel back and forth to attain these readings. The readings are consistent everytime.
I took off the tail stock and gave it a good clean underneath and this had almost no effect on readings.

As far as the mill goes I have issues with the nod this is about 0.1mm front to back when the the head is about 80mm from the table and everything is locked up. When I raise the head to my "normal" work range approx 180-220mm above the table(extend the quill right out) the nod is almost spot on.

The tramming left to right i have got within0.01mm so all good there.

All measurment on the mill are taken with the head, quill and table locked. The lathe measurements are taken with the tailstock and mandrel locked.

Would love some advice especially regarding the lathe vertical tailstock allignment. Anyone on the northshore of Sydney able to maybe come say hello?
Thanks

I probably can't help much with the mill, but I feel I can say I know my way around a lathe ok. I'm on the North Shore of Sydney. Send me a PM with where you're at and I may be able to swing past and see if I can help out.

I'm pulling a spindle at the moment, so I probably wouldn't be able to get around to it until next week, but it depends a lot of course on where you are.

Originally Posted by Maxi77

Hi Guys,
After a few months using my al-960b and HM-46 I am staring to get a feel for them. I figured now that they have been bed in so to speak it was time to get to know them more intimatley and a good opportunity to set them up and take readings of allignments. It has given me time to gain some knowlegde and tackle things I wasn't so comfortable with at the start.

In regards to the lathe I have started taking readings of headstock to tailstock allignment using a mt3 test bar. I have the chuck off and fitted the mt5 to mt3 adaptor and deadcenter. I have got the horizontal allignment within 0.02 mm however the vetical allignment is approx 0.06-0.08mm rising toward the tailstock with the tailstock fully extended. I have ajusted the tail stock mandrel to within 0.01mm on the vertical.
I have the magbase on the cross slide and am turning the carriage wheel back and forth to attain these readings. The readings are consistent everytime.
I took off the tail stock and gave it a good clean underneath and this had almost no effect on readings.

As far as the mill goes I have issues with the nod this is about 0.1mm front to back when the the head is about 80mm from the table and everything is locked up. When I raise the head to my "normal" work range approx 180-220mm above the table(extend the quill right out) the nod is almost spot on.

The tramming left to right i have got within0.01mm so all good there.

All measurment on the mill are taken with the head, quill and table locked. The lathe measurements are taken with the tailstock and mandrel locked.

Would love some advice especially regarding the lathe vertical tailstock allignment. Anyone on the northshore of Sydney able to maybe come say hello?
Thanks

Re vertical TS alignment, the tail stock of a new lathe is supposed to be 0.00 to 0.02mm higher than the headstock center-line. That would be with the TS retracted.

Additionally to the vertical TS alignment error:
- the tailstock barrel itself may not be parallel to the bedways by 0 to 0.02mm upwards only over a 100mm stroke.
- the centerline of the morse taper inside the barrel may not be parallel be to the bedways by 0 to 0.03mm over a 300mm length.

If you add it all up, with the TS barrel extended you should be 0.00 to very little over 0.04mm high at the TS end with the barrel extended. You measured about twice as much. Have you already taken the TS apart? On brand new Chinese machines there often is gunk and/or paint in between the TS upper and lower castings. Sometimes there also are burrs or small dents. After a thorough cleanup and removal of burrs with a file and dents with a stone, you may find your TS is going to come some hundreds of a millimeter down.


Regarding the mill/drill someone else will have to help you. Last time I had a look at these at Hare&Forbes they were very crudely finished for my taste. Much cruder than the Taiwanese Mill Drills, which themselves are no precision jewels either. I think tramming a HM-46 to better than 0.05mm could be a lot of work and time.

Many thanks for the replys, Much appreciated!
Pete F I will send you a PM, Thanks.
cba_Melbourne I have taken off the tail stock and given it a good clean underneath however not felt for burrs so that maybe a simple fix with a light rubbing of stone if thats the case. the mandrel it self i have got running with less than 0.01mm at least relative to the carrige which my mag base is mounted on when I run the Dial indicator back and forth.
I feel the more I measure the more I confuse my self and then its only relevent to how and where the Dial indicator is mounted
As far as the mill goes I dont think I will be doing much with the issue of nod at least i can get it pretty spot on left to right.

I'm also learning from all this for the machines to move a few hundreths of a mm takes very little!

Originally Posted by Maxi77

......I'm also learning from all this for the machines to move a few hundreths of a mm takes very little!..........

That knowledge alone is worth gold!

But also the other measurements you did are not in vain. Knowing how far off things are, lets you use your machine more efficiently. For example, even if you choose to do nothing about the 0.08mm high TS right now, just knowing that it is that much high lets you understand why any hole you ream out with a chuck mounted reamer could potentially be 2x these 0.08mm larger than expected. Knowing this will let you take countermeasures, like use a floating chuck, or guide the reamer with a center, or else.

Big thanks to Pete for taking the time to come over to give me some pointers. Top bloke!
Always good to meet a fellow enthusiast and learn some new tips.

The pleasure was all mine Max, and I like the work you're doing.

I got back into my own workshop and immediately looked for my lathe chuck to fit magnets to

Cool! its all about making life in the workshop simpler and more organised Put the effort into making good quality work
Thanks for your heads up on tool suppliers. I will be taking a visit to McJing's soon