Member postings for Zebethyal

I believe the person in shorts and trainers is actually Dave Kush himself, the author of the website, obviously personal H&S is not high on his priority list.

Many ways to skin a cat, as have already been mentioned, and all have their place, but quite often just because you can use a particular approach does not make it the best or most cost effective.

I could have made the plastic parts for my Buildlog laser cutter by milling them from Acrylic or HDPE or laser cut them from acrylic, but chose to 3D print them, time taken to produce them was much higher, but the material cost dropped from £20+ to pennies, plus I did not need to babysit the printer. The other manufacturing options were all available to me, just as viable for making the parts in question, and would have taken less time but I chose to base my choice on raw material cost.

3D printing for investment casting or mold making are both viable options.

I believe 3D investment printing makes more sense for smaller detailed items where the time taken and filament required to print is low - a friend of mine has had great success with his cuff-link designs, sending them to Shapeways, he uses the various plastic options for proofs of concept and fine tuning the design, then various metals via lost wax investment casting for the finished items, all at reasonable costs (small items).

For larger items, like say a flywheel other methods may make more sense, your more typical wooden mold, or possibly a polystyrene foam investment option.

Building a polystyrene foam investment from regular shapes and gluing them together (mikesworkshop), mill them from foam or use a CNC hot wire cutter for more complex shapes again with the option of gluing on sprues, etc, all with a cost of pennies for the foam even for quite large items.

If you want better surface finish, then try coating the polystyrene in plaster for a smoother finish, then simply bury the item in play sand and cast directly as shown at buildyouridea

Just some more ideas for the pot

I was talking about holiday purchases, where provided the total import value is less than £270.00 per person arriving from a country outside the EU by boat or plane (£1080.00 for a family of 4) there is no duty or VAT to pay.

The shipping costs to the UK from Tormach for 10 units would be around $76.00, plus all of the associated duties on a combined shipment price of $347.50+$76.00=$422.50 (about £280.00), +17% duty, + 20% VAT + £10 = £395.00 or £39.00 each - so not viable compared to Emvio.

Just checked on the price of the Darkon Industries copies and these are actually more expensive than genuine Tormach items at $51.34 CAD (£27.23) before shipping!

Edited By Timothy Moores on 21/03/2016 14:09:02

Hi George,

A point well made, and one I have often made myself on other forums.

I could not recall the shipping price from the last time I saw them listed, and had mistakenly recalled this to be free :D

£10.00 vs £22.00 per item as you so rightly say is not always the full story.

From a personal view point, having a VAT registered company, I tend to overlook the VAT element as I can claim this back, I would however still have to pay the duty element, which, as you state is chargeable on the product + shipping price and don't forget to add the £10.00 handling fee for the post office

I do however regularly stock up on items from US suppliers, not always available here in the UK, or simply cheaper, whenever we go on holiday to the USA - my wife draws the line at lathe chucks and milling vices though

The price for a genuine Tormach holder (ER16, 20 or 32) is $34.75, which works out to around £22.70 (which I can pay when on holiday) with $16 shipping (for 10 via USPS), so for me there is no real saving over the genuine article.

I will agree that for UK based, non VAT registered customers, especially when a voucher is available, these are indeed a good deal.

Yin Sheng Machinery (IGeShi brand at cnccollet.com) used to supply ER20, 25 and 32 TTS collets, with or without the ATC groove at $157.00 for 10 of the ER20 variety (complete with nuts).

Comments from the wider community claimed comparable run out between these, Darkon and genuine TTS collet chucks on a direct comparison test.

They are not currently listing these collet chucks, although they were still listed a few months ago, but I am sure if contacted, they would be prepared to do another run.

If you want a cheap, short, spindle mounted ER32 collet chuck that permits stock to pass through the spindle, how does £19.00 sound?

Buy yourself Stevenson hexagonal ER32 collet block from Arc (£19.00 or £17.75 if bought with the square collet block at £35.50 for the pair), then machine the required nose thread in the rear of the fixture.

There should be enough length of unused stock beyond the end of the ER32 taper to clear the spindle nose threads.

You can then either use a large spanner to remove it, or add some holes for a tommy bar.

Doubles up as a six sided fixture )

Having a Mellor lathe with 1 1/4 x 9TPI spindle thread means that I need to be creative with regards new chuck options, since actual Mellor threaded chucks seem to be rarer than rocking horse poop. My other option of course is to machine my own backplates.

At the TCT show last year, one of the exhibitors was showing off their ability to print with sand, the main application being for casting metal, either using the sand part as a pattern, or as a core. As far as they were concerned, the more complex the design the better, these phenolic sand prints have been used for casting turbines and engine blocks.

Not a new article, but becoming more relevant every day "Free! Why $0.00 is the future of business"

I never bothered with any stops on my X2 Mill, but wanted a cheap DRO to get me by until I convert it to CNC.

I added some Igaging scales to each axis (about £80.00 inc P&P), then made an interface board Link for under £5.00 to allow me to use Yuriy's DRO app Link on a cheap (£43.00 inc P&P) 10" Android tablet.

Similar conversions are shown on the link provided by Den24171 and other links from that thread.

LinuxCNC vs Mach3 - this topic alone can start a passionate debate, both are capable of controlling 4 or more axes on whatever you choose to attach them to, both have a huge following and support forums. LinuxCNC uses a custom 'real time' kernel to ensure correct synchronisation of all signals on the parallel port, Mach3 uses lots of clever internal software to make the Parallel port behave in a similar manner whilst running under MS Windows, ultimately your choice boils down to how comfortable you are with Linux or MS Windows.

USB vs Parallel port - yes USB is newer, but it doesn't maintain the required timing for multiple step/direction signals at near real time which is required for a CNC machine, various 'off board' processors like Smooth Stepper can be used with Mach3 via a USB port (extra cost), the off board processor handles all of the timing signals. You can't simply use a USB to parallel converter, and many laptops don't have a fully connected parallel port.

Many of the CNC router/engravers available on 'the bay' at around £300.00 - £900.00 could well fit the bill, they claim sizes of 300x400mm up to around 750x450mm.

Prices only really go up from there, depending on how rigid and well specified a router you are willing to pay for, the other option of course is DIY - there are hundreds of different approaches to building a CNC router, many of which have open source or free plans.

Personally I run Sketchup on a Mac, I actually find the Windows version slightly annoying by comparison.

To be honest, drawing to exact size is not always the best idea in Sketchup, as this can lead to holes in your model if you try and create intersections between say a cylinder and a curved surface, drawing at 10x or 100x scale and then reducing the model at the end means you have many more virtual pixels to play with and the model remains intact no matter what you do to it.

likewise adding a radius on intersecting edges can lead to holes on the corner if you are doing this at 1mm resolution not the case at 1 metre resolution, attempting a radius on 3 intersecting edges, now that is often quite a challenge :D

Threads, can be drawn, but are not easy, there are plugins for this as well, and to be honest they just end up making the file size huge, for minimal benefit in the drawing - just drawing a cylinder of the appropriate size and apply a thread like surface texture if you want it to look like a thread is usually more than enough (I just tap the threads in any printed parts after printing anyway).

There is a good involute gear plugin, but for most types of gear, I use OpenScad and a very good gear tooth generator from Thingiverse and then simply import the STL file from that into my drawing.

Here is a 60 tooth GT2 pulley, I drew and printed a pair of these using the above method for the rotational axis of my laser cutter (the lower grooves are for a pair of rubber O rings, to grip/turn the item you are engraving):

and a 48 tooth GT2 pulley for the Z axis reduction gearing printed directly from the OpenScad STL file:

Edited By Timothy Moores on 05/02/2016 08:24:29

Edited By Timothy Moores on 05/02/2016 08:50:50

For Nema17 steppers with Pololu/Stepstick drivers at around 1A I use WIckes 0.2mm (1.4A per core rating) stranded alarm flex (12.49 for 30m) and pull out the cores I don't need, individual wires crimped with the appropriate pin (dupont, JST, etc) and inserted into a suitable plug.

For Nema 23 steppers with 2-5A drivers I use 0.5mm CY 2184Y 4 core flex (3A per core rating) available here for 0.48/m or £16.25 for 50m, also available in other cores/sizes and Chinese 'aviation' 4 core plugs and sockets from 'the bay' (thicker cable won't fit the cable grip on the plug).

0.75mm flex is rated to 6A per core.

@AJohnw

Sketchup is not the most intuitive product in the world, but like any drawing package, once you become accustomed to its quirks, you can draw things much faster.

Until you have some form of solid plane within your Sketchup drawing, rotating the viewpoint can throw you in all sorts of weird directions and then take you a while to relocate your drawing!

Personally I start all of my drawings by generating a bunch of guides with the tape measure, starting with the 3 axes at zero offset from the axis (grab the axis with the tape, pull away slightly then back to 0 offset), I then use the tape measure from each of these to generate all of my measurements for a given shape (just as I would if drawing on a sheet of paper with a pencil and T-square/ruler). grab an axis, pull tape in required direction, type in a number and hit enter, new measure is now that distance from where you started in your required direction.

Next I often create a rectangle of some random size against a plane that I am interested in using for a large number of dimensions and then rotate my field of view and zoom in on this (undo to remove it once you are happy with your viewpoint).

Once all of my marking out has been done, drawing lines or shapes is easy, as they all snap to the guides left by the tape measure.

You also know if your line is actually on a given surface if it snaps to the relevant guides - it is very easy to think that your line or surface is part of another surface, when in fact there is a tiny gap.

Extruding is simply a case of grabbing a surface, pulling or pushing in the required direction and again typing a number for distance and hit enter.

Once you have finished your part, you can delete all the guides using the entry from the edit menu, Guides can also be part of a group, which can often be useful if you are attempting to centre a round object against some other item (edit group, create some guides, close group, grab intersection of guides to move group relative to that intersection).

Any movements (pull, push, translate, guide creation, etc) can all be constrained to a chosen axis by holding down the appropriate arrow key at the same time as dragging the cursor (be aware that this is relative to the axes at the time a given group or component was created, if editing that group or component inside a bigger set of groups or components).

A through hole is easily created by drawing your cut-out on the required surface, extruding and then typing the thickness of the material.

if you want to intersect two items, you will need to position them how you require them, then select a suitable surface (outside of a cylinder that is being used to generate a hole in an angled shape)  and then right click and select intersect surface with model to generate the new intersections, next remove the unwanted parts of the cylinder and any new surfaces you do not require.

Hope this helps

Edited By Timothy Moores on 04/02/2016 12:13:10

I built my first 3D printer over several years, abandoning my original set of cast parts for a Prusa Mendel and eventually building a Prusa i3, I am currently building a modified version of a Kossel Mini using 20mm extrusion and delrin sliders (I decided all of the current carriage movements were too expensive so designed my own - now posted on Thingiverse).

I estimate that the first printer cost me around £150.00 including all my mistakes and the second will cost me less than £100.00 (including all electronics and steppers).

I design all of my parts in the free version of Sketchup and use an STL plugin to export files that I can directly import to Repetier/Skeinforge and then generate the Gcode to put on an SD card to print from, it takes a few minutes from saving the STL file to having the Gcode file on the SD card and start printing from it (once the printer has warmed up).

I printed all of the parts for my Buildlog laser cutter, including all of the gears for the rotational axis, as this would cost me a fraction of what the raw material alone would cost me to then mill it on my X2 mill (all parts STL and Sketchup shared on GitHub).

I recently drew and printed some of the stepper covers similar to those that John S showed a few posts back (my steppers have a different screw pattern for attaching them so I could not use any of the existing designs on Thingiverse) and I included the Axis and mill name into my design to personalise them.

All of my trials and tribulations for my various projects can be found on my blogs, all of which can be accessed here: http://zebethyal.blogspot.co.uk.

I agree there is a lot of hype around 3D printing and once most people have finished printing their fill of phone stands, keyfobs, ornaments or parts for other 3D printers, they run out of ideas for what they actually want one for and it then sits and gathers dust.

Edited By Timothy Moores on 02/02/2016 15:50:05

Hi Mauro,

Always good to find another Mellor owner, every one I have seen seems to be slightly different, based on what has been lost or adapted over the years. Mine seems to be missing the thread counter as well as many of the covers and is V belt drive which in itself seems to be quite rare, I also have a 2MT tailstock which I believe only appeared on some of the later models, although the paint colour on the tailstock implies it was possibly from a different lathe originally.

I will have a look and double check, but I believe I dismantled it as follows (not all steps are absolutely necessary as I chose to remove the compound slide first):

Remove the 2 nuts securing the compound slide to the cross slide, these are the nuts securing the compound slide to the 2 T head bolts that allow the compound slide to swivel, this allows removal of the compound slide as a complete unit.

Remove the 4 fingered thumbscrew from the rear of the cross slide lead screw that secures the gear for the power cross feed, remove this gear as well.

Remove the lock nut securing the cross slide handle to the cross slide lead screw.

In my case the handle was held on pretty tight to the lead screw and I needed to jam the cross slide all the way to the front in order to allow me to unscrew the handle from the lead screw.

You should now be able to wind out the cross slide lead screw to the rear of the lathe.

Remove the 2 screws securing the gib to the cross slide and slide out the gib.

You should now be able to remove the cross slide from the lathe.

The cross slide lead screw nut is simply pressed into the underside of the cross slide and can be knocked out is required from the top, or pulled out by twisting the nut from below.

I think this has covered all the steps I followed, please let me know how you get on.

Regards

Tim Moores

Thanks for an alternative idea Bazyle, unfortunately I don't have the space under the cross slide to do what you are suggesting, the current nut at 20x27mm (0.8x1.07" only just fits with little extra space around it for anything else, which was also pretty much stumping most of my ideas that revolved around replacing the screw with an alternative, as the nut would pretty much still need to be a copy of the current one, albeit with a potentially different thread.

Thanks for the link Clive, I read that thread a few months back, before I realised I had this problem and thought it a great idea, but had since forgotten all about it.

I have been considering delrin as a possibility, but was thinking about machining the thread or some way of cutting it with the screw whilst the screw was hot, the method in the link is a much more elegant solution.

My cross slide nut is an odd shape, though not uncommon for lathes (sort of D shaped with a boss on the flat to hold it to the cross slide itself).

There is not much space in the "well" where the nut travels, so I will almost certainly have to go with an almost identical design if I make one from scratch.

The simplest solution may well be to drill out the existing thread in the nut as the unit pretty much is junk otherwise, and use the remainder of the nut as the sleeve to press the delrin insert into.

Hi there,

I will start off with a little bit of an introduction:

A while back I bought a Mellor lathe quite cheaply on a well known auction site, I also have a Sieg SX2 Mini Mill.

I am so far pretty happy with the lathe, I still need to obtain a suitable drive belt to go from the motor to the lay shaft, but that should be simple enough to obtain from my local auto factors.

The reason for this post is that I noticed a considerable level of "slop" or backlash in the cross slide, and after taking it apart, it would appear that the bronze nut is quite badly worn.

The screw itself has a left hand square thread form (not ACME) of 5/8" -5TPI, and whilst there is some wear, it is not that bad. An "as new" tooth at one end measures 0.104", the worst worn tooth is .0965", and most measure at around 0.01" so showing 0.004" to 0.009" of wear which I believe I can probably live with on a lathe of this age that rather than looking to replace it.

The Nut however when wound onto the screw can be moved by about 1mm (.04" ) , with the teeth looking visibly worn when viewed off the screw. On measuring an impression of the teeth, they measure at around 0.065" or .039" of wear, which when combined with the wear on the screw is over 1mm of slop.

Whilst this may be ok for general machining, I believe I will struggle if I need to cut any threads.

Any suggestions for a replacement nut, or any other alternatives, after all, it is not like I can simply nip out and buy a new nut )

I believe I could make the Nut itself, however I will no doubt struggle with the thread as from what I have read, cutting square thread forms is not exactly straight forward and can place big loads on the work piece.

Edited By JasonB on 23/05/2014 15:50:04