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Proteus
14-12-2016, 11:20 PM
Ok, I`m stuck here.
Looking at my toolholders for my VMC300, there`s a difference between them, and the toolholders at Coventry Toolholders.
(http://www.coveng.co.uk/group/coventry-toolholders/products/toolholders-for-manual-machines/easy-change.html)
Mine has a machined groove in the top flange, and i do believe for my ATC holder(spring loaded fork). Se Attached Picture.
However the toolholders at Coventry has not :-\
Looking at the video on youtube, it seems they have 2 types. One With just the 2 notches on each side, and one With additional groove for a ATC Version With spring loaded fork.

Am i completely off track here, or is my assumption correct ?
Are there any drawings in some far away corner of the internet on these toolholders if i would make them myself ?
I could of course make my own drawing and plot it in.
They are a bit expencive if you need say more than 5-10pcs ER32 Easy Change Collet Chucks..

Any advice gents ?

20011

m_c
15-12-2016, 10:10 PM
Have you got any pictures of an existing tool holder?

I'm not aware that Coventry ever made anything suitable for an ATC, and I'd guess the ATC uses a more standard taper. A good list of standards with dimensions can be found at http://www.tools-n-gizmos.com/specs/Tapers.html

Proteus
18-12-2016, 12:19 AM
Don`t know if Coventry Toolholders is the correct one, but i do beleive to remember that name from another post somewhere here in the forum.
Took a Picture of it, and measured som of the Critical parts.
By the way i took a lokk at the link you gave me, but could not find anything even Close to it.

Maybe my Pictures could explain better, or hopefully somebody recognizes the holder...

20022

m_c
18-12-2016, 12:34 AM
Looks like a compact version of a BT30 holder, with a pretty standard pull stud on top.
If my maths is correct, given the height on your photo, the diameter of the top would be about 22mm?

Unfortunately that means it's most likely a custom holder, so getting more will not be straightforward.

Proteus
18-12-2016, 10:28 AM
Yes m_c it does, but the closest i can find is the Easychange toolholder from Coventry.
The diameter on top is 22mm, and yes i think it`s a standard pull stud.
There`s 2 ways i can solve this. One is to send my measurements to Coventry Toolholders for confirmation and ask if they have the Version with the groove in the top flange.
And if the dimensions are the same but without the groove, it should be fairly simple to fix that with my lathe.
The second solution is to make them myself in the lathe. but that one is manual so far(which will produce a lot work work).
I got a bunch of the standard endmill holders with sidelock that i could sell out since i like the onces for collet chucks better.

magicniner
18-12-2016, 12:58 PM
The background grid is 1cm
The tool holder is a Coventry Quick Change

20027

There will be a little parallax but it should give you a pretty good idea of the dimensions and angles,
Regards,
Nick

Proteus
18-12-2016, 06:32 PM
I suspect you mean Coventry Easy Change magicniner?
I`m adding a sketch i made today With all Critical measurements.
.
20034
.
Will also send it to Coventry Toolholders and have them confirm all measurements and explanation as to why the groove is missing in the top flange in their catalog.
Believe the flange is a special Boxford solution on their first ATC`s.. or something...
Would be interesting to know if there`s anybody that would buy any of my bearly used standard Easy Change toolholder like the on in the Picture though.
I`m more into collet chuck toolholders and the Shell Mill Holders.

m_c
18-12-2016, 07:44 PM
explanation as to why the groove is missing in the top flange in their catalog

Because it's not a Coventry Easy Change tool holder.

I've just been and compared one to a BT30, and the Easy Change holders have a steeper taper, which would be correct as the Easy Change holder doesn't use a self locking taper, whereas the BT taper usually is self locking and needs force to remove it.
Unfortunately the battery is flat in my angle calipers and I don't have a spare, so can't give an exact angle.

magicniner
18-12-2016, 09:27 PM
I've just been and compared one to a BT30, and the Easy Change holders have a steeper taper.

Agreed, but I can't find the taper of the mystery holder, if you can enlighten the group with the exact taper of the mystery holder we could measure the angle of the Coventry Easy Change and compare?

- Nick

Proteus
19-12-2016, 12:04 AM
I compared it to the BT30 as well and the angle is different.
Besides the taper length on BT30 is 50,4mm(including the 2mm notch), whereas my mystery taper lengt is 32,75mm.
If it`s not Coventry i`m stuck, but i guess i will receive an answer from them by next week.

Proteus
19-12-2016, 12:07 AM
Still looking around :-x
Measured the angle and although it might not be dead accurate, it reads 21 degrees.
(Se Attached sketch)

20038

I just hope Coventry feedback next week will tell me something...

magicniner
20-12-2016, 12:13 AM
I've measured one of my Coventry Easy Change at 20 degrees

m_c
20-12-2016, 12:23 AM
Standard BT tapers are 7/24, which going by my calculation, works out at 16.26 degrees.

magicniner
20-12-2016, 12:48 AM
Standard BT tapers are 7/24, which going by my calculation, works out at 16.26 degrees.

I've measured Coventry Easy Change and BT30 for comparison/reference with a Moore & Wright Angle Thingy, here's the photos -

I used BT30 because it's the "Taper Which It Definitely Isn't" which keeps getting rolled out here, it mystifies me and I was tempted to use a MT3 taper, but I'll go with the flow ;-)

m_c
20-12-2016, 01:07 AM
It really wouldn't surprise me if Boxford used a custom taper and holder design, just so you had to buy holders from them.

magicniner
20-12-2016, 01:47 AM
Knowing a change in diameter over a fixed height it's a really easy bit of fag packet sketchery and school trigonometry to calculate the taper angle -
Sine - Opposite/Hypotenuse
Cosine - Adjacent/Hypotenuse
Tangent - Opposite/Adjacent

Do they still teach the basics at school? I meet so many people who don't seem familiar with them I do wonder,

- Nick

Proteus
20-12-2016, 08:33 AM
I've measured one of my Coventry Easy Change at 20 degrees

This is why i suspect the tool holders to be Coventry.
My measurement was not accurate holding 2 steel rulers along each side and then measure With a School Plastic 180 Degree Protractor.

Proteus
20-12-2016, 08:38 AM
It really wouldn't surprise me if Boxford used a custom taper and holder design, just so you had to buy holders from them.

I think Boxford and Coventry used to collaborate previously(at least) on toolholders.
I seem to remember a chap talking about some Coventry toolholders for his VMC190, and i think it`s the same toolholder.
Still havent got any answer from Neville at Coventry yet though.

Proteus
20-12-2016, 09:37 AM
Knowing a change in diameter over a fixed height it's a really easy bit of fag packet sketchery and school trigonometry to calculate the taper angle -
Sine - Opposite/Hypotenuse
Cosine - Adjacent/Hypotenuse
Tangent - Opposite/Adjacent

Do they still teach the basics at school? I meet so many people who don't seem familiar with them I do wonder,

- Nick

This is basic Math Nick, but the Challenge is to measure 100% correct top diameter on the taper and correct distance in between(the taper top i slightly rounded).
Tryed to improve my measurements and got lower dia at 31,61, top dia at 20,9 and length at 30. This gives a Cone angle α = 20.24 = 2014' , taper 35.7%.
This is definately no standard taper in my opinion...

magicniner
20-12-2016, 10:34 AM
This is basic Math Nick, but the Challenge is to measure 100% correct top diameter on the taper and correct distance in between(the taper top i slightly rounded).
Tryed to improve my measurements and got lower dia at 31,61, top dia at 20,9 and length at 30. This gives a Cone angle α = 20.24 = 2014' , taper 35.7%.
This is definately no standard taper in my opinion...

Your dimensions are almost exactly what I get off the Coventry Easy Change if I try to measure where you have using digital calipers.
Because of the problems measuring the top edge of a frustum with calipers I chose to measure the OD in two places where an easily measured OD is available, at the bottom edge of the taper and the top edge of the groove, with a micrometer then measure the vertical distance between the two with a vernier, that gives me a calculated angle of 10.02 degrees. (Once I'd downloaded a decent calculator with inverse functions to my phone - what's the use of sine without arcsine Mr Samsung!)

If you super-glued your two steel rules together in alignment with the taper you could draw a nice big triangle on a piece of A4 and measure/calculate the angle ;-)
- Nick

Clive S
20-12-2016, 10:40 AM
I am not into math but the way I see it is that you could put the tool holder into a known dia. hole in a piece of thin stock to measure the top di. then it would be easy to measure the distance to the bottom. Just my 2p worth.

m_c
20-12-2016, 11:36 AM
I think Boxford and Coventry used to collaborate previously(at least) on toolholders.
I seem to remember a chap talking about some Coventry toolholders for his VMC190, and i think it`s the same toolholder.
Still havent got any answer from Neville at Coventry yet though.

The Coventry Easy Change system was fitted to lots of machines, however it doesn't use a pullstud, which is why my money is on some form of Boxford specific custom holder.
Boxford aren't exactly renowned for using established standards.

magicniner
20-12-2016, 01:26 PM
The Coventry Easy Change system was fitted to lots of machines, however it doesn't use a pullstud, which is why my money is on some form of Boxford specific custom holder.
Boxford aren't exactly renowned for using established standards.

The presence on the Boxford holder of the locking ring groove in the same place as on the Coventry holder when with a pull stud it isn't required makes me suspect the Boxford is a modified Coventry, anyone conversant with, say the BT30 holders would recognise that the slot is redundant and that it would be absent on a fully custom-ordered part ;-)
Also there are the suspiciously thin walls above and below the tool changer disc slot, intriguingly designed to fit into the standard Coventry holder drive disc size and position :D

I'll put a fiver on the Boxford being a modified Coventry

Proteus
21-12-2016, 12:10 AM
Got answer from Coventry today.
The toolholders are custom made for Boxford.
Production stopped in 2012, but they can make them at 156 each with the groove. However, i strongly belive it's the same as their standard Easychange toolholder(without the groove).
I will order 1 and check similarity with the ones i have. For nearly 60, i could could even fix that groove myself in my lathe.
The pullstuds however is a Boxford product according to Coventry.
Will have to make them myself ��

magicniner
21-12-2016, 09:45 AM
Jurassic Tools have an ER32 Coventry Easy Change in stock at a good price -

http://www.jurassictools.com/store/search?search=store&phrase=easy+change

- Nick

Proteus
21-12-2016, 12:56 PM
Jurassic Tools have an ER32 Coventry Easy Change in stock at a good price -

http://www.jurassictools.com/store/search?search=store&phrase=easy+change

- Nick

Jepp, noticed but they are out of Stock on the EC-ER32-050, and they don`t have the EC-SM22-015 :-(
But i noticed Engineering Supplies in Hamilton got it in Stock at a good price(approx 76).
They even have the 22mm Spigot Easy Change Shell/Face Mill Adaptor(believe its the same as the Coventry EC-SM22-015) in Stock at 87.44.
Any experience with that company?

http://www.engineeringsupplies.co.uk/tool-holders-easy-change-c-175.html?page=1&menu=1

magicniner
21-12-2016, 01:12 PM
I bought several holders from Engineering Supplies, their shipping was fast and their service was excellent, it's a shame Tony is out of stock of the ER32, I was going to buy another from him for me for Christmas,

- Nick

harvolt
12-01-2017, 04:32 PM
I bought several holders from Engineering Supplies, their shipping was fast and their service was excellent, it's a shame Tony is out of stock of the ER32, I was going to buy another from him for me for Christmas,

- Nick

ive bought and used Easychange collets from Engineering Supplies, Weldon type. work fine in my VMC190. Now, getting the M8 pull studs from Boxford can be pricey enough - 22.17 plus VAT plus Delivery (probably crazy for Northern Ireland)!