Brad93
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Rigidity of the setup. To grind a long mt3 taper.
- Thread starter Tinbasherdan
- Start date
I would have said INT would be preferable to MT. The issue however is that MT is "self-locking" taper and drive is via the taper. With ISO/INT (the difference between them is only in the drawbar thread) the drive is via drive dogs and the taper only exists to ensure concentricity. It is NOT locking and not suitable for drive.
So you would have to fit drive dogs. Which would mean more machining and make it look something like this.
Which may or may not be a problem depending on the spindle design. Unfortunately the http://www.lathes.co.uk/taylormillermk2/ page doesn't show the spindle closely so I can't suggest if it's realistic or not.
Lots of them are very very similar however. For example the difference between CAT/CV, ISO, INT, NT (NMTB), DIN, NFE, BD and BT is largely in the threaded section for the drawbar and the thread itself as they're all 7/24 taper with the same sizes (eg 1.25" at the large end for "30", 1.75" for "40" etc).
Screwdriver
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Just nabbed that NT30 shell mill off Amazon (for a tenner, why not) but am struggling to find a receptacle for it. Would like to at least find a straight (parallel) adapter so I could grip it in a 4 jaw. I am reluctant to turn it down to ~20mm which seems a bit too skinny to drive it on the lathe plus I will one day want to fit it to <whatever it is I have on> the Bridgeport.
I'm somewhat confused... Do you mean shell mill or shell mill *holder*?
If you have a Bridgeport then presumably you want an R8 one such as one of these which take 22mm shell mills
https://www.amazon.co.uk/Baoblaze-Shell-Adapter-R8-FMB22-Machine/dp/B08D72G14C
Face End Mill Cutter, R8-FMB22 7/16-20UNF Face End Mill Cutter Low Cutting Resistance nd Mill Cutter : Amazon.co.uk: DIY & Tools
Face End Mill Cutter, R8-FMB22 7/16-20UNF Face End Mill Cutter Low Cutting Resistance nd Mill Cutter : Amazon.co.uk: DIY & Tools
www.amazon.co.uk
Screwdriver
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Yes that's the chappie thanks. TBH, I thought they would be a lot more expensive. I might turn down that NT30 after all, it fits nothing else in my world anyway.
Matthew Tinker
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I have an SA40 (same taper and size as the INT40)taper in my mill, I have 3 SA40 to morse sleeves, (morse1,2 an3) that don't have drive dogs, they have never slipped and frequently need a deadblow to pop them out! Here in France the SA40/NT40 taper are the most available taper mount!
Cheers, Matthew
SA40 has drive dogs though. That it works without them (and it will happily most of the time) doesn't make it "right". My "ISO 30" in my Harrison will typically need a tap to remove and is almost certainly driving 99.9% on the taper. The drive dogs will stop it rotating though regardless of how heavy a cut you take. You cannot say the same if it's just retained by the taper, would it stall the machine before it slipped?
Machine taper - Wikipedia
Matthew Tinker
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The answer is! I don't know. In my opinion, the draw bar and the taper are sufficient! I would risk it, to be able to have tooling that fits as opposed to one solitary item!SA40 has drive dogs though. That it works without them (and it will happily most of the time) doesn't make it "right". My "ISO 30" in my Harrison will typically need a tap to remove and is almost certainly driving 99.9% on the taper. The drive dogs will stop it rotating though regardless of how heavy a cut you take. You cannot say the same if it's just retained by the taper, would it stall the machine before it slipped?
Machine taper - Wikipedia
en.wikipedia.org
Each to his own, cheers, Matthew
Tinbasherdan
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So, not much progress on the re grinding front. I’m considering buying a cheap collet block and turning a thread and register to screw directly to the spindle nose in place of what would have been the original spindle nut. Any thoughts on why this will/won’t work?
JMS1972
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It's not going to be as rigid as something that engages in the spindle bore but if it works why not?
Tinbasherdan
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Update, I have managed to track down the company with the records for Crawford collets. They have identified the collet type and have forwarded me the drawings for them, as well as quoted me for manufacturing them
Tinbasherdan
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82 quid each :/ might have to have a go at making themExpensive?
JMS1972
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Worth a go!
Maybe make one with a through hole big enough for some sort of collet chuck with a parallel shank?
Tinbasherdan
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That’s certainly a possibility. It was only ever supplied with 4 collets, 1/4,3/8,5/8 & 1/2”. I would presume the metric equivalents would be the ones I want
JMS1972
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Depends on what size milling cutters you can get cheaply.
The MT3 milling chuck I have to go with my one has 6mm, 10mm, 12mm and 16mm collets.
Tinbasherdan
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Tinbasherdan
Bodger in chief
- Messages
- 7,383
- Location
- Bolton, England
Any guesses as to the best material to make a collet?
