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Member postings for Zan

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

Thread: Bridgeport power feed
26/01/2021 23:02:32

My Bridgeport was converted 10 years ago

ill post the circuit diagram in the morning, but

1 rip out all the fuses and anything between vdf and motor

2 wire the vdf directly to the motor use the reverse switch to control only the digital inputs to the vdf or you could inadvertently reverse while motor is running Don’t ask........... I did this while testing after fitting a new drive shaft and forgot.... new vdf a month later......

3 my transformer has a 220 v input and a 440 so former used to give power to the control contractors and the power feed the 12 v is great for led lighting

4 a single 240 contractor was wired up for main power on with a new pair of push buttons on the control panel  I don’t like 240 v going here, but there was no choice  all 240 v power is fed from here to vdf, DRO and an external drive socket 

5 the motor control contractor now just triggers the vdf enable digital . I like this because it enables a satisfying clone when turning on ans enables using my knee to turn off

6 (edit) both the micro switches in my power feed failed by age cracking. So replace these while you are at it!

Edited By Zan on 26/01/2021 23:06:27

ps I run the motor at a fixed speed using the vari speed unit, but it’s noisy and I’m thinking about changing to a direct drive as indicated above. Just worried about cooling the motor at low speeds. The fan at the moment draws a lot of air through the head to cool everything 

Edited By Zan on 26/01/2021 23:17:14

Thread: Electronic Lead Screw Project
21/12/2020 23:34:54

Long reply. Won’t work.. hit code of conduct not post and lost it

Thread: Problem slot milling in lathe
30/11/2020 18:55:04

What moved? The vice? Vertical slide?
I suspect though as already said the slides should be very securely locked.
i think this is mainly a backlash issue. I bet you fed in towards the centre to position the slot. I.e pushing the slide in. The normal cutting tool in turning will be forcing the slide out against the thrust bearing on the screw. Your cutter does the opposite and will pull it in away from the thrust bearing. So you are effectively suddenly giving a setup with little intrinsic rigidity a climb milling situation , and all the backlash will be taken up, thus once any inevitable snatch starts it will rapidly increase

perhaps a way forward is to make it a slightly elliptical slot by starting a cut at the back and feed in FPS out from the lathe centre a trace then go back, increase the depth and repeat . You will still be climb milling but the cut will be of a significantly reduced length rather than the full periphery of the cutter. Best to experiment on an unimportant bit of stock

Edited By Zan on 30/11/2020 18:56:47

Thread: What collet chuck dimentions for s Sieg SX2?
21/11/2020 23:33:16

For my sx2 p cnc conversion I used the R8 spindle this was used with a 3/4 collet and the cutters are mounted in 3/4” silver steel chullets. They are very very carefully clocked in the 4 jaw then drilled, bored and reamed for the cutters held in place with 2x2 ba grubs. Height location is with a 5/32 silver steel bar registering against a machined ring ( in situ) on the end of the spindle. Photo 2, offsets are set off machine in a dedicated setting device seen in photo 1 . It’s highly accurate and the silver steel cost little from a specialist supplier near Harrogate

The advantage of this system is it is ridiculously cheap and has a very very small extension unlike many er chucks , and as Ketamine says, the sx2 is a mini mill and thus the more we can help it the better

The height is set with the dti device in photo 3 it has a length of 115 mm when the clock reads zero when in contact with the work



 Sorry about the aspect ratio!
once the cutters are fixed in their holders the size is recorded from the setting jig in the Mach 3 tool table, and in addition into Fusion 360 which I ciponstantly use for 3D cad and cam code production.

The machine is very well used.   Pm me for more info

Edited By Zan on 21/11/2020 23:34:13

Edited By Zan on 21/11/2020 23:38:57

Thread: Calibrating Micrometers
12/11/2020 19:44:35

Andrew. He said......“ I have bought some second hand 2", 3" and 4" micrometers. Is there any way to check that they "zero" correctly without using a block of known size?”

The only way to zero a 2” micrometer is with a 1” standard you refer to a 1” micrometer 


Edited By Zan on 12/11/2020 19:45:27

Thread: Myford ML7 Chucks - Which one?
10/11/2020 23:19:48

If you get a new Chuck go for a 4 jaw self cantering. They give a very solid grip on material are incredibly accurate and contrary to popular belief they still grip hex material on centre. Despite the warnings above, my 125 mm has been on my well used S7 for 20 years with no ill effects

Thread: Moving a Myford VMC advice needed thanks!
10/11/2020 23:13:14

Looks a nice machine glad it worked out, but two points. Dump the swivel base, I have used mine twice in 20 years so converted it into a horizontal spin fixture.
More important, the vdf is very vulnerable to swarf which will fly far and wide, esp when fly cutting aluminium. it needs a decent ventilated enclosure with mesh to keep the grout out. The one on my Bridgeport is in perforated box mounted on the back of the column

Thread: Milling Speeds for end mills
06/11/2020 22:11:28

Missed the link. Presto information in the “Counsellor” Pages 48 and 50

06/11/2020 21:24:13

There’s fundamental problems with Tom’s tables in the past I have used them but i became exasperated with my copied tables until I realised the error
why? His speed for a 1/4” 4 tooth endmill is 960 in steel with 1 -3/4” feed , yet for a slot drill it lists 1600 rpm and a feed of 3” min. He has the headings the wrong way round! If you follow this point then the tables are very low in cut per tooth

using the 4*cs/ dia yields 1600 rpm ( cs= 100 fpm) Using a feed per tooth as recommended between 0.0005” and 0.002” this yields a feed rate of

fr= rpm x no of teeth x feed per tooth

= 1600*4* 0.001= 6.4 Inches per min.
Tom’s numbers are at the bottom of this range, and he states the tables came from Clarksons Autolock Chuck data.
with more modern spiral endmills with various coatings and the increasing use of carbide cutters in the home workshop, his tables aRe becoming outdated

Edited By Zan on 06/11/2020 21:25:40

Thread: Newmill
01/11/2020 15:47:50

My sx2p came with 4 t nuts as standard. I went for this machine because Of the R8 spindle. Morse taper in a milling spindle is an abomination

Thread: Rubber mat.
01/11/2020 15:36:04

I have several of these. one is about worn out after 10 years
yes they do cut, and are brilliant for

1 collecting swarf so it doesn’t get embedded into shoes

2keeping feet warmer

3 stopping small parts dropped getting lost, they lodge in the holes

Thread: CNC mill questions
01/11/2020 15:32:43


I have converted my sx2 +. Send me a pm n I’ll talk to you

Thread: Newton's 3rd Law
30/10/2020 22:59:24

Perhaps I’m not understanding this. A jet engine produces thrust to an aircraft by pointing backwards, pushing the plane in the opposite direction this idea seems to say if you tie a parachute to the output of the engine, then the plane will fly backwards

Forces work in Equal and opposite directions
But it is a good bit of fun

Thread: DRO errors, or are they??
25/10/2020 09:50:26

Strange! Inconsistent errors. This is where slip gauges are a help

1. Carefully check all the mountings fir movement also the x slide screw, thrust bearing and the nut ( unlikely but it’s for elimination while you are at it, check the gibs) check there is no movement on a dti while the x slide is being locked

2 clamp a block of known size say a 321 block with a bar of flat clamped to it extend beyond say the headstock end So giving two test faces in the same plane
use a dti to set it parallel then feed in to zero on tthe block with the dti then zero the x slide dial n DRO. Check on the clamped bar. After a small movement to clear with the saddle
this will check the DRO and the feed screw

Ha! Some similar comments while I was thinking about this n typing!

Edited By Zan on 25/10/2020 09:53:17

Thread: Reaming Holes in Fixture Plate - What Type of Reamer
23/10/2020 23:46:48

Depends on your cutter. Try it in scrap.

if boring, get the head set to exact size after rough boring. Do this on a bit of scrap clamped On packing onto your tool plate, then coordinate bore all Holes at the same setting

Thread: Grumpy old men
11/10/2020 13:39:18

Tv programs with what will happen in the next part. Very annoying if it’s say part 4 of 6 drama series and it’s a critical point with the story line hanging. If it’s been watched fir this long, why do I need to know what’s next

In a similar vein previews and reviews before and after adverts , is this a way of expanding material to fill the the actual time needed?

Advert intervals which are not 4 mins it makes the time jump on playback trying..... Esp when sometimes it’s only 2 mins.....we never watch things live, saves hours of time a week.....

mr x has apologised/ will not apologise for events which took place years and if not decades ago

dog poo hanging in trees how do they get it up there?
autocorrect on my iPad, and a capital letter at the start of any word you (one) edits
Typing fir not for

not noting down numbers in correct order. Causes mayhem and frustration when parts are too small or too big 2.358” needed, but 2.385” Made , but that’s a silly old git problem Grrrrrrr capital letter!!!

Thread: Inverter connection problems
11/10/2020 10:35:05

Thanks sod and David. Yes I missed the 9-7 at 4.1 ohm I discovered that at 2 am as there was no way for this to happen in a delta connection and found the 7-9, with repeated meter readings, and thus 78&9 could only be connected as a star, after 4 sheets of attempted drawings being the only possible way it would work . However by that time my head was spinning Too much to post!
I was under the impression that any star connection would not work at 240 v however after a lot of trawling with the Dahlander connections (thanks John, the actual name of the connection was a great help) I did find one reference to a star working at 240v but John’s diagram now makes this abundantly clear...

it seems that it was connected in the only way it would work and actually there was no problem at all! That’s The trouble with limited understanding, it’s hard to actually pin down to a faulty motor or inverter, and which caused the problem, one ,the other, or both!

However it’s very good to be absolutely sure I killed this inverter with the momentary disconnection of the motor while changing direction, although it did take a while to actually fail , the first Inverter was I think just bad luck. So now a decision, a cheap £70-90 inverter off the bay or a decent Modern vector type at £180 plus......

I think the latter, as I am contemplating removing the varispeed head because of noise in a home workshop , it’s fine in a massive industrial or educational environment. But I have to use ear defenders all the time when using the machine then the inverter will provide the speed change and I’ll use a multi groove belt .  I enjoy messing about with machines, after building my first lathe as a final year project at teacher training, built a Dore west bury miller, converted a sieg sx2 to cnc and much modified my decker type tool and cutter grinder 

thanks to all


Edited By Zan on 11/10/2020 10:51:39

10/10/2020 16:27:38

Thanks I was using something similar, problem is which wires are which, I have only 9 wires not 12 so which coil is where?

10/10/2020 15:59:34

It seems the left of the diagram fig 1 has been cropped. The connections from the top left are


4 blue

9 red

3 blue

10/10/2020 15:57:12

Single to 3 phase inverter problem

I converted my Bridgeport to 240v in 2005. I ripped out most of the electrics in the control box and replaced the contractors . The inverter was purchased on eBay

The motor was wired up as on the plate for low speed, which at the time I took to be 240 v (Probably not correct). The machine ran so I didn’t try any other connections. I used the varispeed on the 2JB head and ran the inverter at 50 Hz. The motor is two speed when running on 440 v 3phase and it has 9 wires.

The inverter failed in 2009 and was replaced, but when purchasing the new one I was informed the old one could be repaired, at a cost of £20 a capacitor was replaced by them and it worked! The engineer commented that it was a very old inverter. I sold it.

Now the 2009 inverter has failed Of course it was in the middle of an important job! All the ancillary electrics work ok

So some investigation was needed. It seems I wired the motor to a choc block as in fig. 1 from the motor plate as shown in fig.2. It seems that this connection as shown in Wikipedia  is a modified star as shown in fig 3. As the motor should have been wired in delta as in fig 4 it should not have run at all!..

But here is the conundrum, this diagram shows 6 coils so there should be 12 wires not 9. Some must be connected internally, or is it that I just don’t understand the workings of the two speed motor.

fig 5 shows the coil resistance at 2.4 ohms for all but 7-9 and 7-8 @ 4.1 ohms

I have tried unsuccessfully to sort out the diagram to account for this and the grey matter is spinning! I do not know what the colour coding means on the 9 motor wires

It is the inverter which has failed , I connected it to my drill motor ( 3 phase as well) and it just jigged back and forward even with u,v &w interchanged

I will probably get an upto date vector inverter rather than a straight VFD which will cost considerably more.

In February this year, I had to replace a part in the head and made the mistake of switching the rotary switsc from forward to reverse on initial testing. This I know is a big Nono the machine worked ok, but it was noticeable that for a while the motor seemed a bit hesitant to start but it has been worked hard during lockdown.

I don’t want to cook another inverter , so can anybody help with the connections please . I have viewed a lot of manuals and wiring diagrams, but none seem to match my setup.


Edited By Zan on 10/10/2020 16:07:00

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