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Member postings for mgnbuk

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

Thread: Cost effective way of measuring 90degrees very accurately on Milling machine
01/12/2018 16:40:45

No machine is any more accurate than the machine which made it,there is no such thing as Apsolute accuracy ,even at top level.

That is why machine tool builders use skilled fitters - they recify any machining errors to produce machines equal to, or better than, the various machines that contributed the parts.

Nothing wrong with checking out the accuracy of a new (to you) machine & improving on it using time tested techniques.

Nigel B

Thread: RF 31 BENCH MILL DRILL
06/11/2018 13:59:58

Well as the photo shows the OP already has an R8 chuck

The photo also shows a quill clamp lever fitted, so is possibly a "generic" photo of the particular machine & not the OP's own.

Nigel B

Thread: Profiled steel plate
15/09/2018 11:22:49

I use PP Profiles in Batley, West Yorkshire for work - all small orders / 1 offs. They also offer Lumsden grinding to nominal thickness (+/- 0.25mm) & heat treating (stress relief / annealing). They just require a .dxf file of the profile you require. I have found the cut profiles to be clean and accurate to better than 0.2mm, so you don't need much of a machining allowance. Usually a couple of weeks turnround - they post small items & have a delivery lorry for bigger parts.

**LINK**

HTH

Nigel B

Thread: 3 in 1 sheetmetal bender
14/09/2018 16:25:44

I have a Chester 300mm version.

I was going to buy a "damaged-repairable, includes the replacement parts" machine from one of Chester's Hawarden open days (it had a broken foot on one side frame), but it turned out that Chester only had LH frames in stock & the RH side was broken (or vice versa). They offered me a good deal on a new one, so I went for that instead..

Got it home, stripped it to clean off the gunk & deburr the razor sharp edges on all the ground parts, then found on re-assembly that it wouldn't work properly. The holes in the moving bending vee/ guillotine blade holder for the actuating arms were bored out of postion & as a result it wouldn't do all the functions. I took the offending part back,& explained the situation, but Chester had no spares - they arranged instead for the faulty machine to be collected when another new one was delivered. This one I tried before stripping it !

The guillotine isn't great, as the moving blade beam is poorly held back to the main frame & tends to want to tilt when near cutting anywhere the machine's stated capacity - 1mm steel is hard work & the "real" capacity is less than this. It's OK on thin aluminium, but won't touch thin stainless. The bender is OK-ish - it doesn't give sharp corners, but I have not used it much. The rolls work fine - probably the best bit.

It is a heavy little lump & really needs bolting down to a bench to use safely, as you need to swing on the handle to cut and the base is quite short. I have mine G-clamped to an inexpensive Lidl "Workmate", which has worked so far for the limited use it has had - a purpose made stand is on (but probably a long way down) the "Round Tuit" list.. I tried to get clever & bought a second handle on another visit to an open day (the single handle supplied can be fitted at either side), thinking that two-handed operation would make cutting easier. Unfortunately the lever slots are cut in different angluar positions on each end piece, so the levers sit in very different positions !

I sometimes look at it with a view to improving the method of adjustment & support of the moving bending/guillotine blade holder, which I think in requires to be useable, but thinking about it is as far as this has got . So far, not one of my better purchases !

Nigel B

Thread: 1.1 kW electric motor burns up..
23/08/2018 20:11:27

I have a TaiwaneseTrutool branded RF30 mill/drill , which appears to be identical bar the maker's name to the earlier (late 80's / early '90s) Warco Major.

This has a 1.5Kw (2hp) motor, not 1.1Kw as Jens Eirick's Chinese version (and the current Warco offering) has. Maybe the Chinese built versions have been downgraded from the original Taiwanese built machine specification ?

Nigel B

Thread: Inverter advice
24/06/2018 14:46:42

On balance it's probably not worth bothering with the mill but as some have suggested I could get a 220V 3 phase with a VFD for the lathe (which is what I'm most interested in). This would be far more economical than going for a static inverter as they are very expensive!

Depends what you mean by "expensive". I bought one of these for a 415V only surface grinder & also use it on a 3 phase RF30 mill/drill :

**LINK**

Sign up for Machine Mart e-mails & two or three times a year they used to do "Vat free" promotions on Clarke products, which is how I bought mine. No hassle, no faffing with "wrong" motors & the mill will work too - plug & play.

Nigel B

22/06/2018 09:58:38

A further complication may be that some Emco machines used two speed motors - the first picture suggests that this is a two speed machine, as it show 1390 & 2700 rpm at different power ratings on a constant 440V supply. What exact model of Emco machine is this to check the specifications ?

The mill motor is single speed, but Star wound only & I know from (expensive) experience from an FB2 milling machine clone that the star point is not easily accessible to break out the other ends of the windings to rewire as Delta for 220V operation - the wires are very fine, the star point is made very close to the windings and covered by the impregnation, so almost impossible to dig out without breaking a wire off.

I would be looking at a static or rotary converter to supply a fixed 440V supply as the easiest way to get going - I seem to recall reading of people having problems with two speed motors on inverters, but have no direct experience. Or re-motor the lathe with a single speed motor & suitable inverter. The mill motor is a lillte more problematic to change IIRC - I think it is a non-standard frame or shaft size & the nominally "standard" nearest equivalent replacement either has a larger diameter shaft or housing & isn't a "drop-in" fit.

Nigel B

Edited By mgnbuk on 22/06/2018 09:59:28

Thread: Groz metal Bender
18/06/2018 19:21:25

Strange how old posts come back to life !

Like Trevor, my Groz bender has remained in its box (probably the best made part of the kit !) in a rarely opened cupboard since that last unsuccessful outing in 2012.

I have not been able to find out if the DDR original was made from better materials & intend, some day, to remake the too soft parts & poorly finished parts from something a bit better, or maybe get hold of an original if I can find one at a reasonable price.

Michael, I'm pretty certain the Groz copy is closely based on what was marketed here as the Carl Zeiss device, so would expect its theoretical capablities to be the same. When I initially tried it out on some 1.5mm sheet steel off cuts I was able to replicate some of the examples from the instruction sheet, but the poor materials and workmanship mean it is inacapable of heavier work. Quite a nice steel box, though !

Nigel B

(who never was much of a Shakespeare fan - "Slug" Howarth, the English master, saw to that !)

Thread: New Milling Machine - advice requested
16/06/2018 13:04:52

I'm not sure what to make of Optimum Anyone have one?

IIRC Stefan Gotteswinter on YouTube has one of the larger Optimums. Seems like a reasonable machine that he didn't have to do too much to to get it working as he wanted - which is probably at a higher level than most !

Nigel B

Thread: Electric motor reassembly
15/06/2018 17:02:45

The wave washers are to provide a small axial preload on the bearings to ensure that they roll & don't skid if the motor is run unloaded. I would put them back as they were, as they were most likely positioned as the maker intended.

Nigel B

Thread: Dro for mill
15/06/2018 16:03:09

Yes, the Y axis will be fitted to front of table

The table (left - right movement when stood in front of the machine) is normally the X axis - the Y axis is the underslide "in - out" movement.

Nigel B

Thread: Drive Belts - Link or Vee?
15/06/2018 14:56:05

Only had bad experiences with modern, plastic, link belts - both at home (Boxford CUD) and at work (J&S Cylindrical grinder). On the CUD a link belt has to be used, as it goes through the swarf tray to loop around the spindle. The original 1960s Boxford belt used a canvas based link, rather than the hard, shiny, fibre reinforced plastic links used today. Even bow-string tight the new belt slipped under load so, when I had to choose between a Super 7 & the CUD, the CUD went. Similar situation with the J & S grinder, which had 3 belts - we were recommended to use link belts for smooth running, but belt slip limited the load that could be applied (the machine had been converted into a CNC cut-off grinder to slice carbide tubes into short lengths for mechanical seals).

I much prefer raw edge, moulded cog wedge belts, as these conform well round small diameter pulleys, don't need to be excessively tight & drive well. I have no use for a power transmission system that doesn't transmit power when I need it to. Properly maintained (i.e. tensioned) endless belts last a long time, so the minor inconvenience of having to drop shafts or spindles out to change a belt is, to me, just that - a minor inconvenience.

Have not had much sucess with poly-vees in industrial applications either - but that is another can of worms !

Nigel B

Thread: Embossing/Etching
06/06/2018 09:01:08

Do you have a trophy supplier locally ?

We used to use one to produce engraved switchplates at my last employer - they are set up to engrave cups, trophies, nameplates etc.

Nigel B

Thread: Colchester Student 2500 (Harrison M300)
06/06/2018 08:56:44

They are helical albeit very slight.

06062018929.jpg

Somewhat blurry picture of the M330TDI - pretty certain these are straight cut. The bottom (engaged) gear shows wear due to the thread helix angle. The M330 is close to the M300 - vari-speed headstock rather than step gears - the apron appears to be the same as the M300 at my last employment. The gears are 3.2mm thick.

Nigel B

05/06/2018 20:06:59

Technically I think they need to be helical gears, but I expect you could get away with straight cuts at the helix angle of the leadscrew.

I don't think they are that sophisticated, from memory of stripping the TDI down to un-sieze it on the Harrison M330 at work - I think they are straight cut from thin plate. I can drop them off tomorrow to measure up / photograph if that would help ?

Nigel B

Thread: Zero backlash?
02/06/2018 18:01:47

As with many engineering items, Chinse manufacturers can provide suprisingly cost effective solutions. I did a quick measure on the table screw of my FB2 clone - 20 diameter 3mm pitch trapezoidal screw, overall length around 700mm.

**LINK**

This would probably be a reasonable place to start and, at £38 delivered for a 750mm long screw & bearings, isn't too pricy ? This may not be totally backlash free (but it won't have a huge amount of backlash) & probably wouldn't be up to making sub-micron parts on a 24-7 basis, but I would be happy to give one a go at that price if I needed to replace a worn-out screw (or fancied doing a CNC conversion) - particularly as Pro Machine Tools list FB2 table screws at £156, with the nut another £156 !

Nigel B

Thread: KATSU MINI LATHE
02/06/2018 17:45:08

For instance, a centering lathe is a dual head machine in which the work stays fixed and the heads move towards the workpiece and machine a center drill hole into both ends.

The reviewer is not wrong :

**LINK**

Quite how that is relevant to a mini lathe review, though, isn't immediately obvious.

Nigel B

Thread: Zero backlash?
02/06/2018 14:37:39

you will be after the double nut type if you want a preloaded zero backlash ball screw.

Not necessarily. Most ballscrew manufacturers can supply single nut, internally preloaded backlash free screw assemblies. These have two (or multiples of two) ball circuits ground with a slightl linear offset in the nut & the preload is obtained by ball sizing. Ballscrew manufacturers grade balls in micron increments & use these to get the required preload. We used these a lot in my last employment for CNC use, where they worked well and gave long, reliable service. If they lost preload due to extended use, a relatively inexpensive reball would get them going backlash free again. We initially used PGM screws, then Hiwin after PGM were taken over by THK, who dropped the internally preloaded PGM screw range.

We also used German "Star" brand backlash free rolled screws, which had adjustable backlash obtained by a varying the "crush" on the split ballnut housing. They worked reliably as well & were noticably cheaper than ground, preloaded types.

Bear in mind that backlash free, preloaded support bearings are needed with ballscrews to get a backlash free drive solution.

Nigel B

Thread: Bridgeport
31/05/2018 10:27:43

they are less able to 'self lock' so unless you keep a hand on the handles the cutter can pull into the work

In theory. In practice, they work fine - more than enough drag through the slides so pull-in isn't a problem on a Bridgeport-sized machine. None moving axes would be locked via other means, so not an issue there.

I put handwheels on ballscrews on a Taiwanese CNC kneemill at my last employment & ran it as a manual machine for years without any problems using HSS drills, endmills & a 50mm 3 insert face mill. As the machine was built as a CNC carcass it had Turcited ways, so should have been more prone to pull-in if anything - again theoretically, as in practice it didn't happen.

Nigel B

Thread: Arc welder cooling oil.
22/05/2018 09:34:20

Is Brighouse, West Yorkshire near enough ? Millers Oils list transformer oil **LINK**

Nigel B

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