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Member postings for John Haine

Here is a list of all the postings John Haine has made in our forums. Click on a thread name to jump to the thread.

Thread: Cutting Brass Sheet
01/09/2021 09:19:34

Oops! Slow website, multiple posts.

01/09/2021 09:18:49

**LINK**

Thread: Sheet metal saw.
31/08/2021 18:09:16

I've now looked up Shetack saws on the web and looking at the pictures I'm pretty certain that one is meant to cut on the back stroke. The plate has to be very thin to clear the saw kerf so can't have much rigidity. If you pull on the cutting stroke it actually takes pressure off the plate and reduces any bending tendency. I always wondered why Junior hacksaws were so awful until someone on here mentioned putting the blade on backwards, it makes all the difference. Like Japanese saws.

31/08/2021 17:17:48

Put the blade on backwards and cut on the pull? Also recommended with junior hacksaws.

Thread: Overheated Drill
31/08/2021 16:52:24

Builders I have spoken to don't expect even quite expensive drills to last much more than a year or two.

Thread: automating a coil winder
31/08/2021 12:51:10

Hi Andrew,

I posted a build thread here describing a coil winder. As you have the mechanics already you just need a couple of stepper motors and the electronics to drive them. I used an Arduino Uno with a CNC "shield" carrying a couple of DRV8825 stepper driver breakout boards. The Arduino runs GRBL which is a general purpose CNC controller, but it's free and makes life very easy. One can write simple G Code by hand but there's also freeware called Gcoil that will do it for you. For my purposes I load the code on my phone and drive it over Bluetooth from an app called Grbl Controller but you can equally run it from a PC driving via the Arduino serial port. I don't know how much the ELS costs, but you can run GRBL on an Arduino Nano I think, so the total cost of the drivers plus nano is probably ~£30 max.  Then you need a couple of steppers but they don't have to be high spec.

Actually I have the Arduino and stepper drivers in a box that can run either the power X feed and/or a rotary axis on my mill or the winder - somewhere here there's a thread with more details. If this approach is of interest I'm happy to give more details.

John.

Edited By John Haine on 31/08/2021 12:51:55

Thread: Overheated Drill
31/08/2021 12:30:58

I suggest you recycle it, not worth the effort and risk of trying to mend it.

Thread: Cross slide graduations?
29/08/2021 14:54:22

Colin, I don't think you should need a DTI, there's a 2:1 difference and you should see that with a rule! If you nip the rule in the tool post and improvise a pointer in the chuck - a nail would do - position the rule so the pointer is on a fiducial mark, zero the dial, then wind it in one rev. It should read 5mm or 2.5mm depending on the lead.

Some extracts from the thread I linked to earlier:

Muzzer:
"The Colchester Bantam also reads directly in terms of diameter reduction. Once I realised it is fitted with metric leadscrews and dials on the cross slide and topslide (but has an imperial main leadscrew and gearbox!), I was able to see that the dials indicate direct 0.1mm (major) and 0.02mm (minor) increments. I was confused for quite a while by the mixed units, although it seems to be a common situation on Bantams, many of which were supplied to schools.

I measure the actual diameter with a digital caliper and dial in the required final cut directly. Works as intended.
..and later..
...My Bantam cross slide dial measures directly in mm diameter increments, so I can now dial in the required additional cut directly. If I'm feeling paranoid, I can take several cuts and confirm that I am approaching the final diameter from above by using the calipers after each cut.

Murray"

John Stevenson:
"All my lathes are diameter mode.

So are all my drawings

So are all my DRO's

Which then leads me to ask if you have a radius dial on a machine do you program the DRO to also read in radius ?
and

After working on more lathes over the years that I can shake a stick at a few things I have noticed but not exclusive.

The bigger the lathe the more chance it's in diameter mode.

European lathes tend to do diameter more than small lathes or American ones.

Lathes like the Myford probably went radius as it's hard to do diameter dials on small machines due to size restraints and dropping the pitch from 10 to 20 means it wears out quicker."

So some Colchester lathes do work in diameter mode and it may be that different versions were available. If they hoped to export metric lathes then diameter mode would be more attractive.

Thread: clock parts disposal ?
29/08/2021 09:24:14

eBay does have quite a lot of such stuff. The BHI also has a member's forum as well as the HJ that takes classified adverts.

Thread: Cross slide graduations?
29/08/2021 09:22:28

I have owned 3 metric lathes including my current S7 - though on that one the Xslide uses a 5mm pitch ballscrew as it's CNC converted. Its original leadscrew however is 2mm pitch and the dial calibrated 0 - 40 (though of course at 40 it goes back to zero). So dial indicates mm off diameter. Previous dual-dial metric lathe was the same for metric. I've also used other metric lathes including a Myford 254 which was the same.

**LINK**

The link above is to a previous thread here. More than one post covering Colchester lathes and saying that they are calibrated as "diameter".

29/08/2021 08:30:16

Metric lathe cross slides are usually calibrated in mm off the diameter.

So your feedscrew is 2.5mm pitch. This corresponds to data available on the web by a quick Google search.

Thread: A SIMPLE POINT !
27/08/2021 16:53:11

Well, that's cleared that up then!

Thread: Chipmaster motor wiring
27/08/2021 16:52:21

If you forget and open the switch between VFD and motor while running it can generate an inductive spike that destroys the output transistors. Much better to make a direct connection and do the switching and control on the control side of the VFD. For one thing you can usually set the VFD for a controlled accelerate/decelerate time - no need for a clutch.

It won't be so relevant on a lathe, but on a mill for tapping it's convenient to have the motor set for running slowly (say 10 Hz with a large belt reduction), then bring the tap down so it's just resting on the top of the hole, switch on in forward, run the tap to the desired depth then just switch from fwd to reverse. The VFD will happily bring the motor to a controlled stop then reverse with no drama. Try doing that with a normal reversing switch on the VFD output and it would definitely object!

27/08/2021 11:29:57

Indeed John, that is the method, best addressed to Colin though.

Thread: A SIMPLE POINT !
27/08/2021 10:48:59

????

**LINK**

Thread: Chipmaster motor wiring
27/08/2021 09:29:38

Another thought - it's just possible that one of the windings might be "backwards" relative to the other two. It's all to do with the mutual inductances between the windings, which need to all be in the same sense. Are the ends of the windings clearly differentiated (e.g. by labels)? The END of one needs to be connected to the START of the next. If one is incorrect the motor apparently can run "lumpy" - contrary to what is sometimes said it does NOT reverse the direction.

27/08/2021 08:40:27

In what way is it unhappy at 50 hz? The only vfd setting that can affect the speed is frequency and the plate shows this as a 50 hz motor.

Thread: Protractors scaled in Radians
26/08/2021 12:25:30

I'm bemused. I have to work in degrees for measuring things but usually in radians in electronics. It's horses for courses, have to be fluent in both (to mix metaphors!).

Thread: Choosing a boring head
26/08/2021 10:05:09

I have 2 boring heads. One is the generic sort shown in your second link which is OK but adjusting the radius as you get to final size is a bit of a lottery. It takes 12mm shank cutters. The other is an Arrand which takes 8mm cutters and is very much nicer and more precise but Arrand no longer exist AFAIK. I managed to get a set of HSS bits with 8mm shank at a show, I think from RDG but they no longer list them. But ARC list a 30mm od head that takes 6mm cutters and also sell 6mm od HSS tools, so maybe that would meet your needs? Max bored hole size is 52 mm.

Or you might find a much higher quality head used on eBay?

Thread: Myford super 7 with gearbox - leadscrew stopped turning
24/08/2021 09:56:33

Look guys, the headstock mandrel drives the gearbox through a tumbler reverse arrangement which has two settings with a "neutral" in between. If it wasn't firmly engaged in one of the drive positions it could easily slide back into "neutral". From the OP's description it was working fine before going away and drinking the coffee, unlikely to have had a crash when he was drinking it!

Edited By John Haine on 24/08/2021 09:56:44

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