Cutting metric threads

[rebekah andersonParticipant @rebekahanderson95322]

Using a myford ml2 to cut external and internal threads

[rebekah andersonParticipant @rebekahanderson95322]

Hiya one and all,

As you all know i recently bought a myford ML 2.

i want to make the most of it and am looking to make miniature hydraulic cylinders.

Now what i need to know is how to cut metric threads M6x0.5 this is for the ends and caps. Cylinder will be out of steel and the caps out of brass. The caps need the internal thread.

I know it's a change of gears but not sure what ones I need. I'm pretty sure the gears are the same as ML7

I am thinking that a photo may be required of the gears.

is there a tool out there to thread the inside of the cap?

Cheers guys

becky

[MetalhackerParticipant @metalhacker]

Have you thought of simply using an M6x0.5 tap and die. I got a set from Tracy Tools for a boring head I made. Work fine.

saves a lot of Hassle

Andries

[Les Jones 1Participant @lesjones1]

Hi Andries,
I suspect the threads in the end caps for hydraulic cylinders will be very short and even a plug tap will not cut the thread up to the end of the cap.

Les.

[rebekah andersonParticipant @rebekahanderson95322]

That's corect Les, 5 to 8mm deep. That's why I'm having to try and learn how to do this.

[Ian PParticipant @ianp]

I have never seen a ready ground (60 degree) internal threading tool so I think you will have to grind your own, basically a very short boring bar.

You need a good magnifying glass and some patience to grind a suitable tool from HSS, fortunately as the threads are not deep it can be quite short so it will be relatively rigid. (an M3 tap could be used as a gauge)

Apart from having the right gears to give you the 0.5mm thread pitch you either need a very slow spindle speed or alternatively rotate the chuck by hand. I would not bother with a thread dial indicator but reverse the motor to back out (after backing off the tool.

I have cut blind M7 internal threads. also on brass, and it gets easier after the first attempt

Ian P

[Ian PParticipant @ianp]

Rebekah

I'm impressed with your work shown in your album/s. I assume these cylinders are going to be functional but I am curious about what tube and fittings connect it all together, also what are the pressures involved?

Ian P

[Chris HeapyParticipant @chrisheapy71135]

Posted by Les Jones 1 on 20/05/2013 21:00:26:

Hi Andries,
I suspect the threads in the end caps for hydraulic cylinders will be very short and even a plug tap will not cut the thread up to the end of the cap.

Les.

So just grind the end of a plug tap flat, then grind a small chamfer at the end. This would be used to only to bottom out the threaded hole, and using it would be way easier than trying to do the same job screwcutting with a single-point tool into a blind hole.

[Michael GilliganParticipant @michaelgilligan61133]

Suitable Internal Threading Tools are available in Carbide, from Micro 100 in the USA

… They are [inevitably] rather pricey; and I don't know if there is a UK distributor.

Good reference picture though.

MichaelG.

.

P.S.   … just a thought …

With some careful grinding; you could probably make a similar tool from a broken M6 Tap: Lots to grind away; but the profile for the cutting edge is ready-made.

 

Edited By Michael Gilligan on 20/05/2013 21:49:41

[Ian PParticipant @ianp]

Michael

As you say, expensive, but they are carbide. It good to know that they are available anyway.

I cannot make sense of their measurements, reads like they can be used on hole diameters less than zero! even with a one thou diameter shank I think thats a wild claim!

Ian P

[rebekah andersonParticipant @rebekahanderson95322]

Thank you Ian.

They will be working ones. The hose will be coming from a RC model construction machinery shop. (Germany)

I did find this, it's on page 87

 

I know these guys and they aren't cheap but excellent quality.

Chris, i deffinately consider that option.

Edited to shorten link.

Edited By JasonB on 21/05/2013 07:23:16

[Ian PParticipant @ianp]

P.S. … just a thought …

With some careful grinding; you could probably make a similar tool from a broken M6 Tap: Lots to grind away; but the profile for the cutting edge is ready-made.

Edited By Michael Gilligan on 20/05/2013 21:49:41

Not with a standard M6 tap (its 1mm pitch not 0.5)

Ian P

[Ian PParticipant @ianp]

Posted by rebekah anderson on 20/05/2013 21:52:15:

Thank you Ian.

They will be working ones. The hose will be coming from a RC model construction machinery shop. (Germany)

I have just looked at the 'Scale Art' website. There is only one thing I can say about the prices of the hydraulic bits.. WOW!

Then I passed out.

Ian P

[Les Jones 1Participant @lesjones1]

Hi Rebekah,
I have just converted 0.5 mm pitch to TPI. It works out to 50.8 TPI Depending on the pitch of your leadscrew and the change wheels you have you may be able to get 50 or 51 TPI which would probably be close enough. If you give a list of the number of teeth on all the change wheels (Gears.) you have and the pitch of the leadscrew I (And I suspect others.) will try to work out a combination of gears to give a pitch close to 0.5 mm. Contradicting my last post as the end caps are brass it may be possible to start the thread with a plug tap then finish it with a plug tap that that has had the end ground flat. If you try this I would recommend using some kind of guide in the tailstock to align the tap and turn the lathe chuck by hand. I have tapped holes holding the tap in the tailstock chuck and pushing the tailstock by hand. (With the tailstock not clamped to the bed.)

Les.

[rebekah andersonParticipant @rebekahanderson95322]

I shall check the gears. Take a photo and note of the number of teeth along with the pitch of the lead screw.

[rebekah andersonParticipant @rebekahanderson95322]

This is what i want to replicate.

I need 5 of 120mm long ones for the extending boom.

http://www.wpraez.de/xtc/index.php?cPath=13

[Ian PParticipant @ianp]

Rebekah

The end fitting of the ones shown on the wpreaz website look to be capable of taking a reasonable length of thread so using a modified tap is definitely worth considering in Brass. I did not see 120mm ones (if that is the overall length) I notice that the website is very lacking in detailed descriptions or specifications, pretty normal for the retail model shop industry!

What are you using to the tubing?

It need a wall thickness thick enough to take a thread and a smooth seamless bore, is it something available from the model suppliers?

Ian

[Les Jones 1Participant @lesjones1]

Hi Rebekah,
I think it will be a challenge boring the cylinders. I think I would try to find out if some precision drawn tube is available. aluminium may even work rather than steel.

Les.

[rebekah andersonParticipant @rebekahanderson95322]

They don't do 120mm.

Yeah they are lacking arent they. I bought two, one very short and one very long. The caps are short.

The tubing is from here http://shop.premacon.com/index.php?cPath=35_37

might change if i feel the need.

[Tony Pratt 1Participant @tonypratt1]

Centre drill, drill, flat bottom drill and then tapping the caps has got to be the way to go. A spring loaded tapping centre would also be a great asset for this type of work.

Tony

[rebekah andersonParticipant @rebekahanderson95322]

Les,

you could be right.

[rebekah andersonParticipant @rebekahanderson95322]

Tony,

Don't suppose you could direct me to a supplier for a flat bottom drill bit and the tapping centre for a ML2 (MT1)

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Ian Phillips on 20/05/2013 21:53:25:

Not with a standard M6 tap (its 1mm pitch not 0.5)

Ian P

.

But a single profile doesn't have a "pitch"

[the pitch is determined by the changewheels and leadscrew]

I was suggesting a single point tool … same shape as the Micro 100 ones … ground out of a broken tap.

MichaelG.

[Ian PParticipant @ianp]

Michael

I was pointing out that a single point of a 1mm pitch tap will have the wrong thread form (the radius will be much to large). Both 60 degrees though.

I dont know how the ready made miniature cylinders are made but since eache end has to be sealed the threads need to be quite a good fit.

Ian P

[Tony Pratt 1Participant @tonypratt1]

I'm off to bed now but Google gave me some hits on the spring loaded tapping centre as in Gloster Tooling & Chronos. I will have a look tomorrow if some one else doesn't beat me to it.

Tony

[Author]

Posts