Member postings for Muzzer

Another window winder conversion here. Didn't get around to fitting limit switches but worked nicely. Used a variable bench PSU from rapid electronics and a 3-position toggle switch (fwd-off-rev). The winder was 24V and the PSU 0-30V.

The feed could be removed quickly when required - not having a clutch prevented manual operation. A dog clutch would have been an improvement and probably not that difficult to implement.

Of course I soon realised that the correct solution was to augment (not replace) the mill drill with a proper Bridgeport clone.

Murray

Can't pretend to be able to offer relative judgements of different brands but I'd recommend you go for the 3-axis rather than 2-axis. Isn't clear from your post what you plan on that front but you wouldn't be able to upgrade easily later without great expense. I'd also recommend fitting the Z-axis scale to the quill rather than the knee or head if you have the choice.

The DRO was one of the best investments I made on my milling machine.

Murray

Looks very similar principle to the skew chisel used in wood turning. Used one of these a couple of times and it frightened the crap out of me. Best used on small diameters where it is easier to get the angle right so that the edge is tangential and the contact / cutting point is near the centre of the cutting edge. Gets more difficult the larger the diameter of the work piece is. If you get it wrong you better be wearing your best rubber pants - and head / eye / hand protection.

Very sharp HSS tools can produce very fine "bum fluff" swarf and smooth finishes if used carefully (I'm thinking that bum fluff is better better than angel hair!), so I suspect you can get similar or possibly even better finishes with carefully prepared "standard" tooling.

With a suitable holder you could use an insert to achieve this type of cutting - and it would use an edge that is rarely used or even thrown away unused once the corners have been blunted or chipped. The inserts for aluminium are often highly polished and would be good for steel in this application.

Murray

Strange that there was so much response about the coffee; yet no-one has expressed the slightest interest in the chuck design.

MichaelG.

I see that the "other"(?) Tubal Cain posted a video last month about something very similar. Yes, I've just been doing some serious armchair engineering. The old chestnuts like MrPete222 and weldingtricksandtips.com You know how it is - one thing leads to another and before you know it you are in a completely different zone to where you started. No law against it so far!

Murray

Most through hole component leads are left straight nowadays. When manually fitted, they are usually preformed to the correct length before insertion. Large components are held in place with sprung carriers to keep them against the top face of the board before soldering. The wave soldering machines pump molten solder over a raised dam to make it wet the underside of the board. Specially machined shields are used to protect delicate components against the effects of the solder by keeping them out of the solder wave.

Before "the widespread availability of cheap labour", a steel plate with corresponding holes would be fitted below the PCB and a blade run across the bottom of it after the through hole compts had been inserted, often automatically. The plate would be dropped away and the board soldered. When I first started working in electronics product design and manufacture, we were required to have bent leads (before soldering) to provide additional resistance to pull-out. It doesn't seem to have been necessary with hindsight, although it certainly cost many hours of extra effort during desoldering and repair.

As the salt bath Bayzle mentioned uses molten salt, not an aqueous solution, the question of rusting wouldn't apply as there is no water present, even if using sodium chloride. No experience of it myself but I Googled "salt bath brazing" and got some relevant-looking results.

Murray

Induction heating is often used to directly heat workpieces for brazing etc, in conjunction with an inert or reducing atmosphere. The main issue with a cooker hob may be that it's designed to heat a flat surface (pan face) adjacent to the surface of the hob. An industrial heater would often have a hole through the middle to allow more flexibility.

No idea what they look like inside in terms of the induction loop(?) but it may be more useful with the hob surface (glass?) removed, notwithstanding the need to maintain safety isolation between the mains circuits and the workpiece. There is some info on Wikipedia of course. Sounds as if they use an LC resonant circuit operating typically between 20-100kHz or higher. Naturally there are lots of aluminium foil hat wearers who believe them to be the work of the devil but we don't let their sort anywhere near the workshop.

I think I've seen single element induction heaters in places like Aldi. As you say, it would be interesting to hear if anyone has found them useful in the workshop given how cheaply they can be obtained.

Murray

As Ian SC says, some form of oily lubricant is a good idea for parting aluminium. The last thing you want when parting is for the chips to weld to the cutting edge, as this can dramatically increase the load. A decent amount of WD40 seems to help.

One of the benefits of inserts is that the top face forms the chips into a curved shape which is narrower than the groove you are cutting. This reduces the chances of another type of jam.

I've now obtained some aluminium-specific parting inserts from Cutwel for my Korloy parting tool. I'm surprised that they are not highly polished and have an almost flat top surface with the same top rake as the steel ones, so I'm interested to see how they perform when I finally get back in front of my lathe later this year.

The above causes of jams (welding, mechanical) can cause large transient loads on the tool and would kill many of the ground HSS tools. The indexable tools generally have a large blade which is considerably more rugged than HSS. I'm not sue if they are made from spring steel but they don't flinch even when the transient loading is high enough to be audible. I'm sure that alone has been one reason for their longevity in my useage.

Murray

Dovetailed slides aren't really designed to support significant upward ("reverse" forces. Rather than discounting the experiences of users who find success with upside down toolholders, I suspect that some machines (Myfords for one) are safest used with some degree of compliance in the tool holder.

As Nobby suggests, there is more compliance with the tool upside down tool holder than when held "normally". When a tool starts to dig in or a lump of swarf jams in the slot, something has to give. If you don't have a sufficiently rigid setup (arguably the ideal situation), you need the tool to move in a way that doesn't lead to catastrophe. At the very least the tool needs to have some margin of safety (strength) to avoid that deep thunk sound that you feel deep in your bowels.

Personally, I part off in the forward direction and prefer to use inserts. Power feed gives a consistent tool load which is surely helpful. Rigidity also seems to me to be a helpful quality. Ultimately it's each to his own but I try to understand what's going on rather than simply identify something that seems to work and stick to it.

Murray

Hint: try saying "Mercan" with a potato in your mouth. You can substitute the word "American" if all else fails....

Merry

Geoff - you've probably said already on more than one occasion but what is the material and source thereof? Looks like a handy hint to avoid unnecessary cleaning.

Murray

I certainly wouldn't argue with JS's suggestion. If you could get a Boss for "retrofitting", it would save a lot of your time. I bought my manual BP clone without any thoughts of CNC conversion and only started on that route last year. Having said that, I'm more of a machine designer / builder than a scale engine builder so that's what I like doing. Perhaps if I can acquire a decent sized workshop that has room for more tools, I may look into acquiring and retrofitting a proper CNC machine. Obviously I'd be wanting to keep the BP clone!

Personally I'd struggle with anything bigger than my manual BP clone which weighs (allegedly) 950kg, as that's right at the limit of my Weber engine crane. Anything bigger and I wouldn't be able to move it about myself - something I've done quite a bit of over the years.Looks as if a Boss is closer to 1500kg ie 1.5 tonnes.

Converting the CAD models into g-code for the machine is indeed one of the tricky bits. It's a lot easier if you are essentially just operating in 2D but even then, the clever part is getting the tool loads and cutting parameters right. As I'm still at the machine building stage I can't recommend anything with any authority but I'm sure others will be able to. As I'm using Solidworks, I plan to use HSMXpress, which integrates with SW and is free for 2.5D use. Real workshop warriers are able to generate g-code manually for some jobs but I don't expect that's something I'll be able to manage!

Murray

For TIG welding you need pure argon (or Helium), unlike MIG (technically MAG) welding of steel which uses argon with some CO2. So if you have TIG and MIG, you will most likely need 2 cylinders, assuming your MIG is currently used for steels..

If you get a DC-only TIG machine, you aren't going to be able to weld aluminium or copper easily.Apparently it can be done but isn't recommended.

Murray

Have you checked if the brushes have simply worn out? Are you certain the armature is u/s?

Hi Chris

For my X and Y axes, I’m using the 60M-DHT-36 motor, which has 60mm flange (NEMA 23?), 1.3Nm continuous / 3.6Nm peak, overall length 127mm to flange face. The drive is the DYN-2H which is rated up to 750W and operates off 48Vdc. I’ll be running both drives from a 1.2kW PSU I have to hand, although I’m not expecting to be developing that kind of shaft power on the slides of a BP milling machine. The DMM drives can take either analogue or digital (stepper) inputs. As I’d already gone for the 7i76 I/O board which is designed for stepper drives, I’ll use the step/dir signals. Ideally I’d have got the 7i77 instead, which is suited to driving servo drives.

With 5mm pitch ballscrews and 2.5:1 reduction, I’m not expecting to stall the motors! I’m using double ballscrew nuts which you can preload to reduce (largely eliminate) backlash. They don’t cost much more. I even got the ballscrews machined to my exact design for something pitiful like $10 and they made a good job of it.

For the Z axis which I tackled first, I used a Leadshine “integrated easy servo” closed loop stepper which is also NEMA 23 and rated at 2Nm. The drive is built in to the motor and only requires step and direction signals. The technical data on these is a little sketchy but it looks as if they are using vector control which is pretty snazzy for a stepper drive. In contrast, some of the stepper drives out there seem to be little more than an off the shelf stepper driver IC in a box.

I reckon it’s got to be sensible to use a closed loop drive, whether it’s based around a stepper (eg Leadshine) or servo system (eg DMM). Apart from the drive taking care of following the required movement, it can also signal if the positional control is lost finally – in which case you can decide to abort with some level of control.

The Mesa cards don’t seem to be suitable for Mach – all of the info I could find about them was exclusively focused on LinuxCNC. On the other hand, it sounds as if most of the parallel port-based breakout boards will work with Mach. That’s probably not surprising, as Mach seems to be a commercial application aimed mainly at hobby users. I’m not an expert on the history but AFAIK LinuxCNC was originally developed with US government finance and it’s a professionally respectable application. Doesn’t surprise me to hear that Mach branched from LinuxCNC / EMC some years ago.

You can install Ubuntu Linux with a current version of LinuxCNC onto a spare PC and try it out (it’s all free, being open source) if you follow the instructions on the LinuxCNC website. If you have Windows on the machine already, you can make it dual boot. There are “simulation” installations that allow you to run a virtual CNC system without any real hardware. You can install interface boards, drives and motors to them and easily get shafts spinning, then build your system up from there.

Murray

I'm part way into a BP 3-axis conversion. Currently in a state of hibernation due to moving back from Canada to Blighty but hoping to resurrect it asap. The photos and screenshots in my albums are not up to date, apart from the Z-axis which is essentially complete.

My original plan was to drive the X leadscrew directly and the Y leadscrew by timing belt, with closed loop steppers from Leadshine (as used on the Z-axis) but I'm now going with proper closed loop servo motors from DMM Tech with enclosed 2.5:1 toothed belt reduction. These motors claim to give flat torque all the way up to 3000rpm max speed unlike stepper drives and are competitively priced relative to open loop stepper motors and drives.

I could upload some more current views of the assembly and some pics of the compts which I've made (manually) on the machine if you are interested. I've created all the parts and assemblies in Solidworks - don't know if you have CAD? Once you get going, you can obtain most of the parts from the likes of Ali Express and ebay at reasonable cost.

If you are planning to convert large machinery with reasonably powerful motors (mine are rated at 400W ie 1/2 HP but are deceptively small), you need to be careful to incorporate limit switches, e-stops etc to ensure that the thing doesn't go ape and hurt you. Although you can get "breakout boards" from any number of sources, they generally have limited I/O and bandwidth (and questionable parentage). For not much more money, you can get more "proper" interface boards. I've gone for the Mesa 5i25 / 7i76 pairing which has a dedicated FPGA on board (rather than relying on the PC's processor and parallel port) and buckets of I/O. There are other options but as it's only a part of the expenditure, it seemed to me something I'd want to get right.

The other chestnut is the control software. I'm going with LinuxCNC which is open source and free but also pretty professional and well proven. It requires a PC running Linux of course but it's effectively got a proper RTOS, unlike the PC applications. It's also pretty complex ie certainly not quite plug and play. Many people use Mach3 (soon 4) but this is proprietary and runs on Windows but isn't so easy to customise. JAS who also posts here has considerably more experience than me in using LinuxCNC and has his own blog.

There are loads of conversion kits out there and many of them seem to be "hit and hope" or "it seems to work", with little evidence of any rational design process. It's worth looking at the Tormach "white papers" which are refreshingly open about their design process and give you a good starting point. Certainly, if you look at some of the specs for the stepper motors people have used and do some basic calculations, you'll realise many of them are massively overdesigned in terms of the headline stall torque rating. Even if you plan to do a lot of heavy drilling, it's hard to see why you'd need 11Nm motors and sure enough, the professionally implemented machines have more modestly rated servo motors. Many user manuals are available if you look for them...

Hope you find my thoughts interesting / helpful. There's no right answer but plenty of options!

Murray

Interesting to note that early lathes like the Drummonds and Myfords (and my Portass) have "anvil" construction ie you can't easily twist them due to them essentially having only one foot. Not so realistic to design a large machine that way but with my Portass "S", I was never worried about having to level the thing as long as I only nipped the small tailstock bolts loosely.

For the Bantam (which like most lathes also has most of its mass at the headstock end), I try to make sure that the weight acting on each of the two feet at the tailstock end are roughly similar, so that there can be only minimal twist (torque) on the bed casting. Having resilient (rubber) mounts makes the height adjustment of the feet to achieve this easier (less critical). I don't see how I could do much better than this - if there was a slight twist in the bed without any external applied torque, I'm not sure I'd be able to detect it, nor be able to do much about it. However, as I have inherited a lot of farming genes, it's not likely to be a problem to me!

Murray

The electric TT racers were called TTXGP and are now apparently called eGrandprix or eRoad Racing. Many of the early TTXGP bikes used twin Lynch (axial flux "pancake" motors, named after their developer who was also active in the sport. Although they only manage one lap of the IOM TT, they are pretty nippy.

The MGU-K motors used in the F1 cars are limited(!) to 160HP and are tiny. That's partly due to the high speed of rotation but also (as ever) the state of the art design and materials used. And the almost limitless budget.

Murray

Americans traditionally tended to prefer induction (asynchronous) machines in their electric and hybrid vehicles, as they are simpler and don't require the expensive (and foreign) neodymium magnet material. They are also more rugged and larger, which often isn't such a problem with their vehicles. Europeans and Far Eastern manufacturers are happy with permanent magnet (synchronous) machines which are smaller and thus easier to package - but more challenging to design and drive - you need a rotor position sensor for a synchronous machine, whereas you only(!) need a speed sensor for an asynchronous machine. The drives are fundamentally similar to the VFDs we know and love and 4-quadrant regenerative operation comes as standard with modern digital control - it's hardly a technological breakthrough.

Modern vehicles have pretty sophisticated braking and stability systems (by law), so it's not surprising that there's a legally binding regulation (UN ECE 13h) that governs regenerative braking. The idea is to prevent the vehicle losing control due to inappropriate application of large amounts of braking torque. It's pretty complicated when you consider that the amount of braking available will be dependent on the state of charge of the battery and how much power it can accept, so the motor drive must interact with the engine, transmission and vehicle controllers. You'll be glad to know there is also a safety regulation (ISO-26262) that aims to ensure that these systems are designed and validated to meet an appropriate level of robustness and reliability.

Switching the power devices at frequencies above 10kHz helps to reduce the audible noise from the motor but requires more processing power and increases the switching losses in the IGBTs. The Toyota / Lexus vehicles make an audible noise although it's not off putting. I believe they used to operate at 5 and 10kHz.

AFAIK, the university e-racers typically use brushed motors (eg fork lift hydraulic pump motors) which allows for simplicity and pretty much prevents any regen, at least from what little I know of the US scene currently. The drive is essentially a beefy buck converter.

3-phase motors generate a pretty constant torque, unlike single phase machines, which is why they are smaller for the same power rating. The starting torque for a single phase motor is entirely dependent on the auxiliary starter winding etc, as its inherent stall torque is otherwise essentially zero, unlike a 3-phase machine which can generate full torque over the whole speed range, notwithstanding the need for cooling air flow at low speeds.

Murray

Edited By Muzzer on 31/12/2014 12:38:36

Looks as if the Bantam 2000 is essentially a Harrison 250 otherwise I might have been able to help to some degree as a Bantam 1600 owner. They are completely different beasts.

Calling all Harrison owners?

Murray

Sounds as if many of the City Link drivers owned their own vans. Now they are stuck with green and yellow colour schemes and will need to make them white again - and get a job. Good timing. What a nice Xmas present.

Murray