radius on end of bar

[Andrew CresseyParticipant @andrewcressey80402]

Hi can anyone give me any advice on how to achieve this radius either on lathe or mill.I have attached a photo it requires a 37.5mm radius do i need a special cutter or is there an alternative. thank you.

[Andrew CresseyParticipant @andrewcressey80402]

[I.M. OUTAHEREParticipant @i-m-outahere]

Mew #279 – page 55 , photo 119 milling for beginners shows a boring head being used to machine a concave radius in a piece of alloy , you could use the same principle .

A more difficult thing is indexing the now formed radius to the slots and tapped holes then forming the 77mm radius on the outside of the spigot . I’m sure there will be others along soon with a few more suggestions so be patient !.

Ian.

[Andrew CresseyParticipant @andrewcressey80402]

Thanks for that Ian i am all so new to milling this is my first project dont mean to sound dumb but spigot ? could i start of with the solid bar then turn the bore on the lathe then drill the two holes then finally the radius.

 

Edited By Andrew Cressey on 15/05/2019 15:35:58

Edited By Andrew Cressey on 15/05/2019 15:36:43

[JasonBModerator @jasonb]

I'd do all the turning then drill the two small holes. You can then poke a couple of pegs or drill bit shanks into the holes and use those to line things up when clamping the work.

Cut the radius with a boring head, at that radius you probably want the tool sticking out the side hole of a typical 2" boring head rather than the end. A flycutter could be pressed into service if you don't have a boring head.

Another option is to mount the work on the lathe cross slide and use a between centers boring bar to do the curved cut

[Andrew CresseyParticipant @andrewcressey80402]

Thanks Jason i do have a fly cutter so i just extend the cutter out to produce the correct radius then would i go up and down the end of the bar cutting in deeper at each pass?

[JasonBModerator @jasonb]

Best thing is to locate the end of the work below the spindle and then move away by the radius eg 37.5mm. Fit the flycutter and adjust the cutter so that it just kisses the edge of the work as you rotate by hand which will get it swinging the correct radius which then does not get altered.

Once that is set use a series of downward cuts moving the work towards the spindle say 0.5mm to 1.0mm at a time. I tend to use the quill lever for the initial roughing passes but the last one or two are best done with fine feed

[Andrew CresseyParticipant @andrewcressey80402]

I understand that so i put the cutter above the bar and set it to the correct radius then back it of to the end of the bar and take small cuts at a time drawing the cutter closer until i reach the desired radius is that correct? excuse my lack of knowledge but i only have a clarke mill and lathe and never used either until now.

[Andrew CresseyParticipant @andrewcressey80402]

So far i have built this from my drawings but drawing 1,2,3 i find difficult to grasp.

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