Myford ML7 - QCTP - Quick Change Tool Post


I replaced the old original Myford turning tool clamp assembly with a Dixon type quick change tool post from Chronos.

The QCTP is clamped into place using the original Myford toolpost and the 7/16 inch BSF toolpost nut.

I eventually replaced the Myford ML7 toolpost nut.
Continually locking and unlocking the QCTP with a spanner is a nuisance.
This modification did away with the 3/8 inch Whitworth spanner, and was one less tool to have laying around the lathe.

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↓ I got the QCTP set from Chronos.

Set No = 390201
Size = Small
Set contents = 1 main tool post -390200
Set contents = 3 standard turning tool holders - 390204

At a later date, I bought another 10 standard turning tool holders when they were on offer, in lots of 5.

The turning tool size is limited to a height of 8mm.
Larger turning tools can be used if 2mm or 3mm is skimmed off the Myford top-slide. I will not be doing that modification.
Larger turning tools can be used if the bottom of the tool holders are skimmed down. I will not be doing that modification. I feel it would weaken the tool holder.
Larger turning tools can be used if they are milled down to 8mm. I suppose you would do that to save money and use what you have.


The QCTP brand is Soba. The machining on a couple of the holders was not completed. Luckily it is just a cosmetic fault and does not affect their operation.
To be fair to Chronos, they would have replaced the faulty items without question, if I had asked.


↓ The existing nut on the toolpost was replaced with a much longer nut.
The new nut is a bit too long to call a nut, so I am calling it a locking post.
The existing toolpost is not modified in any way.
To complete the job, I bought a set of carbon steel 7/16 inch taps from Tracy tools. Their carbon steel tooling is considerably cheaper than HSS. I went for the lower quality carbon steel as I will seldom use the 7/16 inch tap. It was hard work tapping the thread; the CS taps do not seem to be as sharp as HSS.

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↓ There is a brass washer at the base of the locking post.
There is a recess in the brass washer. The locking post sits in the recess in the brass washer.
The recess keeps the washer and the locking post neatly in line together.

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↓ There is a deep hole in the main post of the QCTP set. I cannot figure out why it is there.
One end of the handle is turned down to 6.8mm diameter.
The thinner end of the handle,allows me to conveniently park the handle in the hole in the QCTP. Happy days.

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↓ Here is the assembly sequence.

↓The existing Myford toolpost thread.
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↓The recessed washer.
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↓The locking post and handle in position.
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↓The handle parked in the hole in the main block.
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↓ The dimensions for the new QCTP locking assembly are :-

Locking Post - OD = 19mm
Locking Post - Height = 79mm
Locking Post - Thread = 7/16th BSF 18 TPI
Locking Post - Threaded Bore Depth = 45mm
Handle Length - Overall = 122mm
Handle Length - Thick End = 99mm
Handle Length - Thin End = 23mm
Handle Diameter - Thick End = 10mm
Handle Diameter - Thin End = 6.8mm
Brass Washer - OD = 23.16mm
Brass Washer - ID = 11.1mm
Brass Washer - Thickness = 4.7mm
Brass Washer - Recess Depth = 2mm
Brass Washer - Recess Diameter = 19mm

All parts are fitted to suit each other, and the dimensions are approximate.

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