Help with what metal lathe cutter needed

[Neil Mccarthy 1Participant @neilmccarthy1]

Hi all I am looking at a tool that can make a 5mm grove in different types of metal I am making some safeties for my air rifles I have attached a picture of the part I am struggling with is the gap between the 2 bigger bits which is 5mm wide the end bit of fine but I can’t get the other bit with my tools it needs to be a 12mm tool that’s what my lathe takes and something to do a 5mm gap

thank you

**LINK**

[Neil Mccarthy 1Participant @neilmccarthy1]

[HopperParticipant @hopper]

You could use a parting tool. Either a bought in one or grind your own out of a HSS blank.

[Neil Mccarthy 1Participant @neilmccarthy1]

Hi thank you is it easy to make one I have a grinder I will have to look on YouTube I’m sure I will find out on there thank you for your advice if I could make a 5mm one would save me a lot of time

thank you

[HopperParticipant @hopper]

What you need to be able to grind all your own tools is one of these: **LINK**

We used to use them back before there was YouTube and they worked very well.

It has the easiest to follow and most comprehensive guide I've seen to grinding your own HSS toolbits with a standard bench grinder. Or you could buy a standard 3mm wide parting tool and cut a 3mm wide groove with it and then move the carriage along 2mm and widen the groove to 5mm that way.

Edited By Hopper on 25/02/2020 04:21:19

[Neil Mccarthy 1Participant @neilmccarthy1]

Thank you I will buy that and read up how to make them and it will teach me more things that I need to know as well

thank you for your advice

[HopperParticipant @hopper]

Posted by Neil Mccarthy 1 on 25/02/2020 02:09:05:

Thank you I will buy that and read up how to make them and it will teach me more things that I need to know as well

thank you for your advice

Oops I missed your post. See the addition mine above re using a standard parting tool to do the job. But buy the book anyway. It is invaluable for learning to use the lathe.

[not done it yetParticipant @notdoneityet]

The lathe tool shank size is irrelevant as long as it does not exceed the largest size it will take.
Just grind away most of the tool steel before actually grinding the cutting part.

For such a small cutter, it would be better to use a much smaller piece of HSS as a starting point – packing material below the cutting tool is far cheaper than HSS and there is no need to get the top of the cutter at the correct point, as it can easily be adjusted.

Adding a scale to your pics would help to give the scale of the item.

I will note that these safety catches appear to only prevent the trigger being pulled. Safer than nothing, but it does not prevent the mechanism discharging like an intercepting sear would.

[JasonBModerator @jasonb]

I would suggest using a narrower tool, trying to feed a 5mm wide tool into what looks like a 5mm diameter workpiece will more than likely end in disaster. 1mm or 1.5mm tool plunged in to rough out and then moved sideways to finish the bottom would be what I would do.

[Neil Mccarthy 1Participant @neilmccarthy1]

Thank you everyone

[Howard LewisParticipant @howardlewis46836]

For small diameter material it will be better to use a narrow tool, taking several cuts as the toll is traversed sideways, to the same depth.

The larger the tool holder the more rigid things will be, so a narrow toolbit can be held in a substantial holder.

It is important that the tool, being slim does not overhang too far in the the interests of rigidity.

Obviously the tool must be kept sharp, and set on the centreline to minimise cutting forces.

Howard

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