Member postings for Muzzer

That's a common misconception but you should save your worry for something else. The torque of a synchronous motor (including stepper motors) is proportional to the movement from the commanded position ("positional error". If you generate 10x microsteps, you haven't magically redesigned the motor. Each microstep now represents 1/10 of the fundamental step - and oddly enough a movement of the motor by a 1/10 of a step from the commanded position generates 1/10 of the torque. It has the same torque vs angle behaviour, so it will behave in exactly the same way as the un-microstepped motor, assuming the driver is capable of processing the higher frequency pulse train.

Murray

I had a whole series (5) of Honda Accords until Honda stopped selling them in Europe. Ended up getting a BMW and the contrast couldn't be more disappointing - the Which reports claimed it was reasonably reliable. Once the short warranty has run out, the dealers coin it in. Costs an arm and several legs to run, goes through tires and brake pads like they are going out of fashion and parts fail all over the shop. The Hondas pretty much never went wrong. Like never. I'd trade it in for a Korean alternative if I could actually find a large estate from those environs.

Murray

The "SCLCR" designator tells you what the toolholder looks like and what insert it takes. It's an ISO std (as is the insert designation). There's a quick guide here although most manufacturers will include it in their catalogues of industry std tools.

No idea about the "BBPT" markings. Suspect they are a proprietary system that may predate the ISO std.

Murray

Edit - should have said that the SCLCR is probably the most common boring bar style we encounter. It takes the CCMT / CCGT inserts although be aware there are several different sizes.

Edited By Muzzer on 16/11/2018 20:57:32

Interesting. I was a beta tester for Onshape back in Feb 2015 and found it quite a refreshing alternative to the premium priced alternatives I had access to at the time (Solidworks and Solid Edge). In many respects it's rather like Fusion 360, particularly in terms of the interface and the "joints". It was actually set up by the team who originally implemented Solidworks, so they knew a thing or two about CAD.

The aspects that put me off were the limitation on the size and number of files you could work with before requiring the professionally priced subscription and the cost of the plug-ins. Unlike Fusion, the core product is CAD only and they rely on 3rd parties to provide "connectors" to their programs. So for CAM, they have connectors to the likes of Sprutcam, Mastercam, Visualcam etc. However, these are professionally priced and the closest I found to being affordable back then was Sprutcam at a cool £1000 a pop. Coupled with the cost of the cheapest subscription, that was pretty steep for hobby use and I've also tried to keep an eye on being able to access my work in the future, having created work in a few different systems.

What Onshape and Fusion have in common is a subscription only system, which removes much of the barrier to first users. Companies like Solidworks, Autodesk Inventor etc insist on not only an eye-watering initial purchase price but also an eye watering "maintenance" contract which has to be maintained if you want technical support and the critical updates and "patches". They get really grouchy if you drop the support and won't reinstate it later unless you make the missing interim payments. Sheer greed. However, it opened the way for subscription products that seem to cost less than the maintenance payments.

I can't actually see a CAM plugin called Parasolid CAM in the Onshape app store - is there a link to it somewhere?

Murray

The Atom version is pretty well cut down, so check the comparison table carefully. The Pro and Expert versions are £940 and £1540 respectively and if you want to use any of the non-basic features, that's what you'd be looking at.

And £475 for a basic 2.5D CAM option, described as "A modelling and milling package tailored for sign makers, hobbyists, makers and students". Not much use if you put it up against modern multi axis packages. The Fusion CAM is actually HSMWorks, used professionally in many sectors. If you plan to get into CNC at any time, think about it now.

Once you've got the hang of one of these CAD systems, it's not difficult to learn another one. However, I wish I hadn't had to go through the process so many times along the way, each time investing dozens of hours in the process.

Despite the shallow accusations of tribalism, I'd suggest you take a look at Fusion 360 which will cost you nothing and is a very capable, professional system, with full feature 3D CAD, simultaneous multi axis CAM, FEA simulation (stress, thermal, vibration etc), rendering, sculpting, sheet metal, 2D drawing etc.

Right, I'll duck again now...

Murray

Edited By JasonB on 14/11/2018 15:39:13

When I used Geomagic a few years ago, I discovered that it wasn't possible to add a thread feature to a revolved surface, only an extruded one. That's all very well if you have got to that point by extruding a series a cylindrical features one after the other, end to end but often it's easier to create a section and revolve it. When I mentioned that to the rep (in the US), he made some snidey comment like why would you want to do that. Ok, so why offer a modelled thread in the first place came to mind. Have they fixed that yet?

Murray

Haha, yes, I heard that the Mundano DMF is prone to premature failure!

It's not an inherent problem with DMFs so much as the supplier / engineers who cocked up specifying / validating them. I recall spending hours with an Indian customer who was very wary of them on account of a bad experience with them, as if they were somehow beyond being properly designed but most diesels have them these days and there are many examples that are trouble free. They give the effect of a massive flywheel with much reduced moment of inertia.

Murray

Yes, his was one of the positive reviews that steered me towards the Cetus.

And here's my first impressions with photos.

And the pros and cons from my viewpoint as a summary.

Murray

Edited By Muzzer on 09/11/2018 14:23:30

Hexavalent chrome has been banned from automotive products for some time now and there are plenty of adequate alternatives for the various applications. I suspect you are right that there is no (or insufficient) interest in (finding) an alternative. Perhaps that is why legislation is often required and not just implemented willy nilly.

Murray

Pretty much 100% of automotive and consumer electronics are built using lead free solder today. There are no issues with it unless you would have had problems with leaded solder anyway due to poor process control. If there were issues still, you'd be able to look out of the window right now and see thousands of cars careering to a stop, your phones and computers wouldn't work and you'd have no telly to watch. You probably won't believe me when I tell you that a typical car these days has over 50 microcontrollers in it - and something like an S Class will have "quite a few" more. Think of how many solder joints there will be, all of them lead free....

Thermal cycling certainly isn't an issue with modern solder. The default lead free solder is SAC305, so called because it contains 3% silver and 0.5% copper, the rest is tin. There are enhanced versions such as "Innolot" which are optimised for high temperature operation with extra thermal cycling - I've used this on turbocharger actuators that have to withstand continuous operation at 180C with operation down to -40C, including validation testing alongside std SAC305 parts. No problem with it at all.

AFAIK it's actually illegal to use leaded solder on potable water joints in the UK and has been for some years. That doesn't stop you using it on central heating pipework where it's easier to get a sound joint on large diameter pipes. Illegal if you are a tradesman that is. They won't come and march you away if you are dumb enough to continue using leaded solder in your own house plumbing when there are good alternatives.

Murray

I recently bought a Cetus3D printer for under £340 delivered. This included the bonus pack which contained 2 large reels of PLA and several different sized nozzles. Took minutes to screw the subassemblies together and I had it up and running in no time. This one has wifi and like most it comes with its own software and slicer. It also has an iOS and Android app which is perfectly capable of running jobs and monitoring progress.

At the weekend I created a plastic terminal cover for a servo motor in Fusion 360 and saved it as an STL file, then printed it out on fine resolution over night.

Here's what it looked like in the Fusion modelling environment

and also rendered in Fusion just for fun.

Pretty impressed with the finish - it's just as good as what I was getting from the Ultimaker 2 which costs about £4k last time I looked.

There's an optional heated bed and you can get your own off ebay etc for £30-40, complete with digital controller if you want to use ABS etc.

Once the raft and supports are removed, the final result is pretty darned good. The M20 x 1.5 threaded hole was just right for the cable gland and the surface finish is excellent.

There's no enclosure and the std printer has unheated bed but the quality of the work is very pleasing. The printer itself uses Hiwin machine slides, which is a pretty neat approach. You can do a lot worse for the price and delivery was something like 2 days from the UK warehouse.

Murray

Joe

This damper looks to share some behaviour with dual mass flywheels (DMFs) although it uses the centrifugal force on the slugs to make them behave as if sprung to their default position, ie storing energy as potential energy (radially), resulting from rotational speed variation. DMFs generally use a circumferential helical spring to store energy due to variation in rotational speed, although I do recall one that had a mass mounted on 2 large dowels, rather like an inside out version of yours.

I guess you'd be able to tune the effective spring constant in your damper by changing the diameter of the holes. Larger holes = lower spring constant. As you say, there is no actual damping element per se unless you introduce some sort of viscous medium which could be messy! I suppose you could get the sums wrong and end up with an unhelpful resonance just where you don't want it but you seem to have avoided that.

Murray

I see it's one of the Iscar TGFH parting tools. Different inserts to the "GTN" used in many (most?) other insert tools. I was provoked into getting one recently after similar reviews here, on offer from Zoro (Cromwell).

I found it worked nicely on steel and loominum. Not quite 125mm but it looked as if it would cope if the time came.

Murray

More likely to be IGBTs than FETs, same story in microwaves - usually but not always. IGBTs have a better current density than FETs in the silicon die, so you need less silicon to achieve the same switching capability. Bottom line is that they are more cost effective.

Murray

Just be aware that when you save in a generic format such as IGS, STP or STL, what you are saving is not parametric ie you can no longer change the dimensions of the model, you lose the design history and often the dimensions are not exactly how you created them. It's possible to use "direct editing" in some programs but you are still not working on or creating parametric models in that mode.

Similarly, if you actually found another CAD program that would import native Alibre models (I've yet to find one), you would lose that parametric data, while any assemblies you imported would lose their mates / joints. In the end, when I tried to resurrect previous "orphan" files including Alibre (Geomagic) CAD models, I ended up printing out the 2D drawings and recreating them from scratch in whatever I was using (Solidworks, Inventor, Fusion etc). There's no clever way to do it.

Not trying to pee on anyone's parade (accusations of tribalism etc) but be aware that "save as" has distinct limitations as a way to pass models to other systems. Spoken from experience...

Murray

Klueber who specialise in bearing lubricants recommend 1/3 - 1/2 of the free volume but it depends on the speed too.

Useful Klueber reference here.

Murray

Yes, these things are utter rubbish. As a former engineering and research director at an industrial battery charger company, I looked into quite a few of these. They operate at the barely legal end of the market (in terms of claims) but the bottom line is they are successful at parting money from punters but not much else.The most successful ones have managed to obtain some form of patent application to strengthen the illusion but that generally doesn't prove anything.

Murray

And there was me answering David Jupp's question about features.

You're sailing close to the wind here, Neil! You appear to be actively promoting a commercial product yet closing down objective discussion.

Murray

Well, I guess if Neil had chosen to give F360 a free promotion, there might have been a similar take up. Of course, as F360 is free anyway, the concept of "promotion" has a different complexion. With Atom, it's effectively a delayed payment (or option not to buy if you don't get on with it) but it's still a significant purchase by another name.

I believe Autodesk's repeated promises not to charge for hobby use but if it ever happened I suspect it would be some years in the future, at which point there is likely to be a reasonable choice of good quality / good value CAD and CAM - and many of us will be in the armchair / workshop in the sky. by then. In the meantime I won't be looking the Fusion gift horse in the mouth. It's a pretty darned amazing product and when you get into CAM, there are very few products that come close in terms of features and price - or total lack of price in this case.

I wasn't planning on saving my bank details on the Fusion / A360 cloud and I'm struggling to think any of us would have anything to be worried about keeping our own funny little designs there.

Murray

Edited By Neil Wyatt on 27/10/2018 15:53:30

I tried that. It was as buggy as hell, kept crashing and was missing some major features. Whilst I applaud open source, self-funded programs, up against F360 there is simply no comparison. Probably not surprising, given that F360 is being developed by a fully funded team of professional software engineers with a major corporation behind them. You wouldn't find many professional users betting their businesses on FreeCAD, unlike F360.

Murray

Edited By Neil Wyatt on 27/10/2018 15:53:25