3 – Jaw chuck on Clarke 300 lathe / cutting speeds for brass / steel.

This topic has 10 replies, 7 voices, and was last updated 16 February 2012 at 09:33 by Ian S C.

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12 February 2012 at 22:10 #5948
Chris machin
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@chrismachin
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12 February 2012 at 22:10 #84573
Chris machin
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@chrismachin
Hi All , My clarke 300 is fitted with a 3 – jaw chuck and i have tonight taken out the jaws to see if they can be fitted as external jaws to give increased work holding capacity. It appears not so my question is are external jaws avilable and where do i get them ?

Also can someone tell me a general speed for cutting / facing both brass and steel. I have tried facing brass tonight and seemed to get a good finish around 2000 RPM , Is this a good general speed for brass. As yet i haven’t tried any steel cutting.

Many Thanks

Chris.
12 February 2012 at 22:23 #84576
Ketan Swali
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@ketanswali79440
The outside jaws are supplied with the machine. Look in your bag of bits.
12 February 2012 at 22:31 #84577
Chris machin
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@chrismachin
Hi , I Bought the machine second hand and there are no other jaws with it .Hence wondered if they can be purchased seperately ?

Thanks
12 February 2012 at 22:57 #84579
michael burton 1
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@michaelburton1
hi chris go to your local machine mart if your in the uk and they will be able to get them for you you may be able to get them if you phone there help line or service centres

Tel: 0871 410 1270

Email: [email protected]

thats the contact details for the spare part centre

hope to help mikey
12 February 2012 at 23:10 #84581
Chris machin
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@chrismachin
Thanks for info Michael , I’ll give it a try
13 February 2012 at 16:17 #84644
colin hawes
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@colinhawes85982
The speed for cutting a metal bar depends on its diameter and material.Also the rigidity of the machine. Using HSS tools on mild steel ,about 700 rpm would be ok for 3/8″ to 3/4 dia 500 rpm up to1″ dia but cutting the larger sizes you should use a cutting fluid of some sort to maintain tool life and finish. 50% higher speeds for brass and aluminium. Note that, without lubrication, aluminium tends to weld itself to the tool causing a torn finish. Smaller diameters will be cut at proportionally higher speeds. I hope this gives you a good starting point! Of course ,you can’t achieve ideal speeds when facing the end of a bar because its diameter is not constant.

Colin.
13 February 2012 at 20:00 #84671
Russell Eberhardt
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@russelleberhardt48058
Best cutting speeds depend on many factors. There are tables of recommended cutting speeds in M/min or ft/min but these are just a rough guide. If a certain speed works for you for a given job stick to it.

Your speed of 2000 rpm for brass would be fine for up to about 3/8 diameter. You will probably need to reduce the speed proportionally for larger diameters.

Russell.
15 February 2012 at 14:13 #84829
Joseph Ramon
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@josephramon28170
As you can vary the speed continuously you can change it if the tool is struggling or you get chatter. You will learn more and get better results by experimenting this way than by using calculated speeds. The right speed for a job depends on tool shape and sharpness as well as work diameter and material. You will be surprised how being able to change the speed helps you learn and how little you change it once you get used to the lathe.

Joey
16 February 2012 at 09:00 #84888
Russell Eberhardt
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@russelleberhardt48058
Agreed, the published tables are mostly for industrial use where the machines and tools are more rigid and speed of production and tool life have to be weighed off against each other. For hobby use with less rigid machines the requirements are different. The tables can, however, be used as a starting point.

Russell.
16 February 2012 at 09:33 #84895
Ian S C
Participant
@iansc
One you missed Russell, coolant, in industry the cutting fluid goes on in liters a miniute, enough to cool the work to ambient temperature while it’s machined at high speed, and big cuts. The lathe is completely covered in, its a completely different world from ours. Ian S C
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