Author Topic: Machining of internal lathe workpiece  (Read 539 times)

Offline AlexS

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Machining of internal lathe workpiece
« on: December 24, 2021, 11:36:46 AM »
I've always been asked which tool is best for light and medium lathe lathe work.

Especially for turning internal machining. There are different chisels, only which one is most suitable for turning cylinder liners, for example.
I don't know the correct English translation for the tools, but have added them as images.

For external machining when turning long length steel without support from the tailstock, I get a lot of vibration and is accompanied by a lot of squeaking and ugly machined surface. What did work was to always support it with the tailstock when machining long length (more than diameter).
My lathe is a Myford ML7, I have already checked the radial play of the spindle with a dial (method like shown in Youtube link). Around 0,02 mm measuring on the 3-jaw chunk when applied force on the chunk. The spindle bearings are not new and showed some wear. But I want to be sure if it's my way of machining or fixing of the materials.


Other thing, I want to machine a cylinder block. There has to be a space where there can flow some coolant or oil around the cylinder liner. I can find tool like shown in picture 4, can these do the job or are there better ones to do the job? This is new for me :)

Offline Thor

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Re: Machining of internal lathe workpiece
« Reply #1 on: December 24, 2021, 12:26:33 PM »
Hi Alex,

 The tool in your second photo could be used to make a start on the groove for coolant, some of the tools in the fourth photo could probably be used the get the correct angle on the sides of the groove if they are long enough to reach the end of the groove. Good luck and Merry Christmas.

Thor

Offline Roger B

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Re: Machining of internal lathe workpiece
« Reply #2 on: December 24, 2021, 12:27:43 PM »
I use the second type insert tool boring bar with DCMT style inserts for cylinder boring. Mine has a 10mm shank and will just enter a 13.5 mm drilled hole (the largest drill with a MT1 taper that fits my tailstock). This will cut a water jacket around 2 - 2.5 mm deep. For a deeper jacket I use HSS boring bars like in you last picture but they are not so rigid and tend to chatter. Luckily the finish inside the water jacket is not important. My last efforts at this are here:

https://www.modelenginemaker.com/index.php/topic,10605.0.html
Best regards

Roger

Offline Jasonb

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Re: Machining of internal lathe workpiece
« Reply #3 on: December 24, 2021, 04:00:58 PM »
For cutting the cooling recess I would just use a simple home made tool. Nothing more than a piece of round bar cross drilled at one end to take a small piece of HSS and drilled and tapped at the end for a suitable grub or cap head screw to retain the HSS. Tool bit can be ground to whatever shape you want, keep the diameter of the bar as large as possible as this will help reduce chatter and vibration.



Offline john mills

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Re: Machining of internal lathe workpiece
« Reply #4 on: December 26, 2021, 08:28:39 PM »
I have  used tools as jason shows the bar should be as large as you can get in the hole  the high speed  ground tools will work well on the out side  turning  too and on small machines will get better results .for longer shafts ground tools that are sharp will cut better.  .
John