Member postings for Muzzer

Interesting. I've been paying $40(US) per kg reel of 3mm ABS (www.botfeeder.ca). That's about 2.5p per gram for the material ie a long way from 50p per gram. Presumably the 50p figure includes equipment amortisation, operator time and commercial profit?

BTW Ian S C - the Cubify printer requires proprietary replacement cartridges for the filament at about $100 (60 quid) each on Amazon.com, which may be a reason not to get one. It has a chip to prevent you replacing the filament yourself but it looks as if hackers are working on it....

With so much open source software about nowadays and 3D CAD becoming cheaper (and taught in schools and colleges), I’m not so worried about the missing step between the idea and the CAD model. There’s a whole generation coming through now that simply accepts this as the way things are done. The current 3D printers are like the dot matrix printers of 25-30 years ago (in more ways than one!) and I’m sure they will become more robust and commoditized pretty rapidly. And with milling, routing and laser cutting heads already being added, you can see that we aren’t far off having some pretty interesting equipment at our disposal. These are basically miniature CNC machines and even use the same g-codes for the tool path. Give it time…

Our printer at work (Ultimaker 2) has now got about 100 hours or so on the clock and we’ve used it for making samples of connectors, cable clamps and small junction boxes for customer and certification use, while non-work examples have included a chain protector and jockey wheels (for a mountain bike) and a proper sized mug holder (for my car), which would be almost impossible to make any other way. I also made up some parts for the screw cutting clutch I’m working on, to get a better feel for what it would look like in the flesh (I posted pictures earlier - they are in my "stuff" album). You can go from CAD model to test sample in as little as 30 minutes for a simple part, or let it run overnight if it’s a larger part. The default density is 20%, which means that it generates a honeycomb structure inside the part to save material. However, you can change that all the way up to 100% if you need a solid part. And this plastic is actually pretty tough.

I’ve been working away at my 3D CAD skills recently and the mug holder was a nice test of my capability, combining thin walls, draft angles, swept sections etc. Nice to be able to print out what you have to verify you’re on the right tracks. As I said, there’s no realistic way to make one of these using any other process. If you are sensible where you buy the filament, the cost should be a few pence per gram, so the mug holder for instance probably cost less than 2 quid. The final part will be in black, with a better surface finish but at this stage I'm able to check it fits the vehicle and finesse the dimensions. Not a very good photo, sorry.

Murray

I may have missed a post somewhere above but one option that would combine the best of several options would be to use stepper motors - but without using a micro to generate the speed signal. You could even take the opportunity to use a 555 for that purpose. No software required - no need to master Arduinos, Raspberry Pi's etc.

You could buy a couple of stepper motor drivers that simply require a speed signal (= frequency of step pulses) and a direction signal (high or low). If you common the speed inputs and set them up to have the same number of steps / microsteps, you will end up with identical speeds and positions. You can buy drivers and motors at robot shops, ready to go.

Without a position or speed sensor, you simply can't synchronise the speeds of 2 conventional (= brushed) DC motors, even if you have several PhDs. And even with that feedback signal, it's not a simple business.

Murray

Tonight's challenge - add some 10mm ventillation obrounds to the lid of a steel battery cassette for a fork lift. 21 of them of various lengths from 60 to 160mm on 3 different faces. The lid measures about 60 x 50 x 20cm. In production, these would takes seconds on a CNC punch but I don't have one of these and it's already been folded anyway.

So the Blidgeport went in for a bit of serious yoga. Couple of angle plates, cassette hanging of the back of one side of the table then the other, table and ram fully extended, turret swiveled right then left. Being sheet metal (1/8", it was never going to be possible to clamp it rigidly, even without the various overhangs. Pretty noisy business, lasting just over 2 hours, a lot of it setting up. And thank god for power feed.

Stretch to the right....

...and stretch to the left....

Done now, including deburring. Managed not to ding the carbide slot drill and it's still cutting nicely.

Not the most fun I've had in an evening but a reasonable result given the circumstances.

Merry

Can't get rid of that smiley that thinks it's a right parenthesis....

Edited By Muzzer on 04/03/2014 07:04:19

It does go as far as to say modern neat oils do not pose this threat.

Hi John

As a power user, what neat oils have you found to be best? Obviously if you avoid mixing with water, the bacteria can't feed and thrive but I've little experience beyond water soluble suds and WD40. Perhaps I should think about changing - and neat oils probably cut better?

Thx

Merry

This always polarises opinion but I'll reiterate what Mike, Shaun etc said above. If you take a fine (and / or slow) finishing cut you'll most likely end up with a worse finish. Ideally you'll take nice deep cuts and run your machine near max speed. You don't always need a lot of power - my Bantam is only 1.5HP and manages quite happily. I use power feed on both axes where possible and increase the speed as the tool approaches the centre line.

This is what I manage using carbide inserts. The 2 disks are 4140 carbon steel (rather like silver steel) and the shaft is some sort of mystery stainless steel I recovered years ago from the Ark. Not a touch of emery paper in sight. With experience, frequent measuring as I go and careful use of the micrometer dials I can get the final dimensions within a thou or so despite taking a decent final cut. If I undercut it, I take a shallower finishing cut and get out the emery paper but I try to avoid that.

It's a good idea to sacrifice a piece of material for some experimentation, rather than learning the hard way on something that matters. Discovering that increasing speeds and feeds improves the finish significantly with indexable tools is a major step forward. Same goes for indexable parting tools, which I also used for parting off those disks with power feed. Stuff takes a lot less time to do this way....

Murray

Boring bars and fly cutters can't hold a candle to a solid piece of HSS or carbide - they are considerably less rigid. When a well maintained twist drill is working near its capacity, it's producing 2 continuous spirals of almost full width swarf. You'd only try to reproduce that rate of metal removal with a boring bar or fly cutter once even if it had the same cutting edge length. Hole saws have no means of swarf clearance, so you have to use a series of micro pecks to clear the swarf (dust!). Even during a peck, the rate of metal removal is pretty modest.

The main reason I use a pilot hole is to ensure it starts centrally and to avoid the central core of the drill needing to cut. Although they are designed to drill without one, they need a greater force to advance the drill without a pilot.

I have had issues with keyed chucks slipping but not with keyless (apart from cordless drills). That's presumably because the keyless chucks are inherently self-tightening.

I had a GM-era Saab 9000 for less than a year. Lovely car, very comfortable and solid, lots of comforts. But after the engine grenaded a couple of times we found ourselves leaving the Saab at home when we had to go any distance and instead packing into a miserable Citroen diesel we'd been given. Eventually I saw sense, sold both and went back to Hondas. Paid my dad 2 grand for it, spent 2 grand on it, sold it for 2 grand and did less than 2000 miles. Would have been cheaper taking taxis. Never had a confidence problem since.

The guy who forced the sale of Rover to BMW was the same idiot who oversaw the demise of Lord Weinstock's GEC. Rover was only a few years into a long journey to change their quality culture. Honda was never interested in owning them, just being a cross shareholder as is common with Japanese companies. Funny thing is that a Rover often cost more than its Honda equivalent. Used to make my toes curl when we were told to buy British. Said idiot was made a Baron for his services.....

Absolutely disgusting the way Towers and his buddies sold off Rover assets for their personal gain and left the employees on their own. The final chapter of a shameful story.

Edited By Muzzer on 19/02/2014 18:53:41

Dangerous to generalise but anyway. Generally the Japanese and Korean companies are the top tier, followed by the Germans/GM/Ford in the middle and the likes of Renault, PSA, Fiat, Chrysler (and remember Rover?) etc at the bottom. Funny thing is that VW got away with making out they were very reliable yet were only ever average and more recently very poor (the power of marketing). Another funny thing is that Skoda (also part of the VAG group) made very much the same vehicles as VW but their vehicles were/are noticeably more reliable. I worry about Nissan, as they are co-owned by the same company that owns Renault.

Quality is a cultural thing that is very hard to change, much like a personality. Hondas are often referred to as the engineer's car! Yes, I have owned a long string of them, as well as a range of outliers for reference....

Merry

Yes, they are both pretty good illustrations of the technique although I suspect this isn't the first time the approach has been thought of. Cast in place methods were probably commonplace when white metal was used for bearings.

Murray

I recall a dental technician friend of mine showing me a rather nice metal Polo Mint he'd made using the lost wax process which is what is used for casting dentures. Not sure what metal he'd used (after the passage of much time!) . When I remarked that Polo Mints don't melt as easily as wax and presumably result in residues, he said they simply used higher temperatures and left it in for longer. Presumably this is enough to oxidise any carbon that forms. Sure enough, it was a very clean part.

Murray

I saw a thread on another forum recently that described splitting the unthreaded nut lengthways into 2 halves and then gently heating the leadscrew and clamping the nuts so that they moulded to the leadscrew and each other as they melted.

Just found it - it was Jim Schroeder **LINK**

Worth a go?

No idea which forum you're talking about. Call it paranoia if you want but it features in industrial safety literature, so probably not just superstition.

Rather like machine guards - failure to learn from other peoples' experience is stupid in my books. Your call.....

I'm never comfortable leaving oily rags and tissues lying about. You might think it's a bit far fetched but in some circumstances they can self combust without the need for a flame or spark. I don't think it's clear what conditions are needed for this to happen but it's clearly a risk, not folklore. If you Google something like "spontaneous combustion oily rag" you can see there is some basis for the notion.

Never had a problem with it myself but I try to keep old oily rags and tissues in a steel bin away from other flammable stuff. I don't want to discover the right combination of constituents!

Murray

Sorry, I assumed this was one of those Daily Mail / Jeremy Vine type threads, given the title. I just got kind of drawn in without realising!

Merry

I see the tribe over at Mensa are still milking each other's vanity ("The High IQ Society"!!). Having Sir Clive Sinclair as Hon Pres pretty much says it all for me. Last I heard from him he was proposing fuel cell powered helicopters. What a national embarrassment. The danger of spending too much time in front of the mirror...

Be aware that proper MAPP is no longer manufactured. Instead, a slight of the marketing hand is used. The replacements come in the familiar yellow can along with (suggestive) names such as "MPP" (and probably "MAP Pro" I suspect). However, they burn a lot cooler than the original MAPP and seem to be based on LPG and propylene. To be fair, the Bernzomatic "MPP" substitute sold here in Canada is spelled out as "Max Power Propylene". However, in this case with some oxygen to spark it up a bit you are probably back up there.

BTW, I know you Aussies like to think you are hard but why would you want an oxy-gas kit to solder ("Bromic Oxyset Soldering Kit"?

Merry

You might suggest a compromise solution whereby they send you the replacement foot and reimburse you some of the original price for your trouble. With some companies this might be as much as 100% reimbursement but that's a good starting point for a discussion. To a Scottish-blooded Yorkshireman like myself, this could be a very satisfactory solution. And it would allow you to focus on the job in hand again....

Merry

Yes, sounds like it.

Note that for D1-4, the diameter of the (external) conical taper is 63.5mm. If it measures 54mm, it's a D1-3. The Bantam also has an MT5, so clearly it's used on machines with both D1-3 and D1-4 and different spindle bores.

The critical dimensions for the MT bores are presumably the major diameter and the taper angle. Whether or not the bore extends the "full length" matters less.

Murray

Embarrassingly, when generating a CAD model for the spline shaft, I noticed that it actually has 8 splines. Ho hum! Anyway, I should be able to derive the coordinates from that to enable me to machine one up with a standard end mill. Once on the rotary table, I can always finesse the finished part to fit the change wheels if it's not spot on. The splined shaft I'm working from has taken some wear over the years so I can't take consistent measurements from it.