Member postings for Russ B

Martin, I have the Aldi one (£149.99 delivered last year I think) - the blade tension is fine, I could play a tune on it and the weld is flat and smooth, I'd be taking it straight back before they have none left to exchange it with if I were you! (And hoping its not a crap batch!)

I bought a 3 pack of Milwaukee variable pitch 44.7/8" blades (1140mm) but I'm still on the original M42 blade after over a year (although I recently chipped a tooth manhandling dexion profile, my own fault) - they were very cheap delivered, worked out circa £6-7 a piece or something?

Milwaukee do 10, 14, 18, 24 TPI and 10/14 and 14/18 TPI variable pitch. Not all of those are available in europe in the more economical packs of 3 or more blades, so it takes a bit of looking around on the net. I can't for the life of me find where I got mine from, I'll have to check the bag/box in the garage for clues.

Jeff,

As I suspected, very expensive to do properly! I already have polyurethane and silicone casting equipment as I made a valve head and cast a PU sealing face onto it for a small (by my standards) injection machine (typically pulverised or pellet fuel injection)

I might contact the local supplier to see what other options might be available as the PU i have would be too soft although probably chemically compatible.

I’m still going to gave a look at this DIY machine, i’m too curious.....

Chris/Jeff,

What if I only want 10-20 of a particular part, what are the costs involved?

Jeff, the piston is connected via a gudgeon pin, you can't see it in the screenshot as it's the same colour as the conrod, I just modelled the one in for stress anaylsis, the opposing pin will obviously feature equal and opposite stress. The head of Cylinder is flat and removable to aid cleaning when the jobs done.

I have one of the finest, if not the finest FFF 3d printer on the market so I can print the model myself. I'm looking at a small 6mm pipe connector with a 1-1.5mm wall thickness. We're looking at about 55mm total length, the most difficult part I want to make is a 4 way cross.

Chris, it's always good to have some companies to call up, thank you, putting injection moulding terminology and quieries into google is a waste of time, I was trying to find out how NBR parts are made the other day to see if I could make my own and it was like I was asking the meaning of life, every answer was totally different and none hit the mark!

Jeff,

Thanks for the input, regarding clamp force, I had planned on justing bolting the two halves together, as I don't mind making one, then waiting for it to cool, taking it apart and making another, I'm not really trying to brake any speed records, maybe half a dozen in an hours, and I'm happy.

The barrel/nozzle are fixed, I'm relying on a brass piston in an aluminium bore to maintain it's own alignment, it's a sqaure piston diameter to length, 25mm diamter, 25mm skirt, I could easily extend that skirt to 30-40mm if I have any problems with rev1.

It sounds like I won't be getting the finest quality parts, but I will be testing and gather quite a lot of data and see what works best. I will keep in mind "hold up" time, obviosuly it's a 1 shot wonder, but I don't know how long I need to leave the material in the got barrel before I consider it to be thoroughtly melted and ready to go so given your comments, I'll test parts for strength having given them maybe 2, 4, 6, 8, 10 minutes heating up, see if a sweet spot appears??

Edited By Russ B on 02/11/2020 16:08:38

It might be worth checking out, do you recall when/where it was?

I have pretty muich done the basic design, it all used either M6 tapped holes or M6 clearance. I haven't made the die support yet as I'm not sure the square column will take the stresses involved as it was much much higher than I anticipated, so I will check the column isn't going to bend or stretch, then take it from there!

Well I've drawn up some plans of my own as no one came up with anything!

The design I've put together looks like it should do the job, I have no injection molding experiance but some knowledge. A friend of mine (also an engineer) used to specialise in injection molding so I'll be running the design and numbers past him and see what he thinks, its obviously going to be a long and crude way away from what he's used to!

The hand lever arrangement I've designed offers around 3.5kpsi of injection pressure with a relatavily achievable 50kg pull on the handle. I just need to check the stress on several other components as the handle and lever had to be very substantial after looking at the stresses involved.

I've ordered a pair of temperature controllers, one for heating the cylinder, one for heating the die (as I expect 3.5kpsi of force won't be enough to inject my rather large part into a cold die.

Once it's up and running I'll make several "rods" of plastic for tensile strength testing and compare strength and cooled size vs die temperature to see if there is much effect on finished strength. I may also connect a loadcell to handle and measure strength vs injection pressure.

I think it'll be ok, it'll be interesting to see strength vs die temp and how much shrinkage is observed.

I've cut 60mm solid EN16 steel bar with mine, no trouble, and significantly quicker than my power hacksaw, smooth as silk.

Worth noting, the motor doesn't seem to heat up, thus it doesn't seem like it's having a hard time, I apply just enough pressure to feel/hear the saw cutting and let it go at it's own pace from there. I always use the minimum speed on the variable dial.

I got the £150 workzone one from Aldi, it came with an M42 bimetal blade, which has now lost a tooth after years of use. I was cutting up some 7m lengths of Dexion free hand and it snagged and chipped a tooth, no biggie.

The vice on mine is not very good, it uses a cam to advance and lock the vice jaw, and if you press the jaw against the part theres no room for the cam to rotate and "grab" and the part can jump out! (You have to set the jaw a mm off the part, then lock it)

Ironically just less than an hour ago, I liberated a fixed jaw and screw type vice off a damaged Makita saw from work, looking at it, thinking this is a much better design! The one coming up at Lidl has the exact same screw type vice design with the quick release nut!!!!!!

What were the chances!!

Edited By Russ B on 29/10/2020 13:15:35

I'm looking to reproduce some plastic pipe connectors, I can very easily source standard Tee's/Y's etc but I really want an exact reproduction of what the machine should have and the parts are incredibly basic in shape.

Does anyone have a simple DIY arbour press type plastic injection molding machine they'd consider selling?

I have been looking at making a simple aluminium cylinder with a pair of chinese ceramic heaters and a close fitting piston, a basic chinese PID temperature controller, fitted to a fabricated arbour press type stand, simple, cheap, effective - but it would take me a while to make, so I thought I'd ask if anyone has one they don't use anymore.

Regards,

Russ

Not sure about the Raglans, the 280 looks identical in many ways to the Harrison M300, same bed casting, same saddle, same headstock casting but the two speed change levers are mounted on top of the Myford but are still basically the same inside the box. The apron and the screw cutting box are different but elsewhere the similarities seem never ending!

It seems no one knows anything about their manufacturer but I’ve seen so few out in the wild I wonder if they ever produced them in any reasonable quantity. Someone must know something, I’d assumed they were made in nottingham but never seen any photos of the production, whereas there are many pics and history of the rest of the range. I’d be surprised if they weren’t made by Harrison.

Thanks, i’ll take a look. The lathe came with a user manual and parts diagrams but I don’t recall seeing any maintenance info beyond oiling etc

Edited By Russ B on 19/10/2020 19:40:40

Does anyone have a pdf manual they could share with me for the Colchester Bantam or Harrison M250, I just want to make sure I’ve adjusted the spindle bearings properly on my Myford 280 which looks like it’s cut from the same cloth as the above two machines.

Well, I got there in the end!

After all the trouble I had with the crossfeed dial I decided to strip and clean the compound, which turned into a full strip and clean of the compound slide.

Interestingly when I stripped the much smaller vickers dial, it was actually exactly the same internally, the graduated dials were just machined down to around 3/8th larger than the press fit hub as per martin’s photo above actually, you can see comparing his dials to mine, mine have much more meat on the dials!

After some comparison between the two, I reached the same conclusion but for a different reason which is kind of important just in order to understand what went wrong. Basically the press fit steel hubs internal spigot had been machined or rubbed down, presumably damaged OR a replacement part intended for what looks like the later design that Martin has NOS of? So when the knurled wheel was tightened, rather than locking the steel hub/graduated dial to the shoulder on the shaft it was pushing it into the steel mid plate. After machining the mid plate down there was then a small interference with the gear carrying backplate that retains the driven wheel and mid plate, only very minor, a quick hone and everything was as good as new, almost. The locating peg that holds the driven half of the assembly in place is a bit damaged, and slotted more than it should be! The whole assembly has obviously seen some abuse.

So all functional now, albeit without the imperial readout as I had to remove the damaged pinion gear.

Edited By Russ B on 10/10/2020 10:17:16

I have the B&Q cheapo hoover, wet and dry etc, has lasted me 8-9 years of hard use, building works, wood work, swarf oil etc. great piece of kit, i’d go straight out and buy another if it died tomorrow.

So, my steel mid section is actually thicker than yours, exactly 3/16” in the centre. It’s obviously been rubbing this for some time as it’s worn down a thou around the edges.

I’ve determined from careful measurement and sketches an interference between the steel mid plate and driver wheel of 0.1305mm or 5 thou, it’s right there on paper, double checked the dimensions and laid it out twice.

No way around it, it just doesn’t work.

If my mid steel plate was 4.5mm like yours, I’d have exactly 5 thou clearance..... sounds comfortable to me.

I need to get some 4.5mm plate or find someone with a small surface grinder!!

This where I got the idea maybe I was missing a shim on the shaft, to space the wheel off the steel plate slightly.

Edited By Russ B on 07/10/2020 22:11:27

Those photos confirm no shim. Is the driver dials steel hub pressed flush with the graduated gear ring (the side against the table in your photo)

Does anyone know where the little plastic gears can be sourced.

Size wise i’m not sure how big mine is. I’d say they functional top slide one is about 1.1/2” maybe 1.3/4” and the troublesome cross slide is maybe 2.1/4 ish, from memory which just looking at post seems to make sense.

The fixed steel mid section is thicker on yours with countersunk screws, mines just a plate with regular pz2 screws (not metric)

Yes the photos would still be very useful considering mine still doesn’t work on reassembly!

As i’ve said i think the steel hub isn’t pressed all the way into the driver/dial. This steel hub locates against the face of the first step on the shaft and because the gear/dial is standing proud it’s locking against the middle fixed steel plate when there should be a very small clearance I had initially wondered if I was missing a shim, but given the close tolerances of everything, Vickers probably didn’t need to shim anything!

Edited By Russ B on 07/10/2020 12:48:10

Martin I look forward to your reply.

I have now managed to get in to it. The two tapped holes are a red herring, they secure the centre steel plate to the backplate retaining the driven gear/dial.

It was simple a case of tapping the threaded end of the shaft back though the assembly. It was incredibly tight due to damage and burs on the shaft from a previously botched repair. To worsen matters the black steel hub which is a press fit into the driver gear/dial has been beaten to death with a hammer on the inside spigot which is a close fit inside another shaft, which caused it to seize.

Add to this that the press fit hub isn’t pressing all the way in, and they are the main causes of the issue. Someone’s had a go at fixing it, and beaten it to death. I’ve done my best to dress it up with a file and stone but Vickers really put some close tolerances on these things so it’s still drags slightly here or there.

I need to determine why the hub isn’t pressing all the way in tonight because it’s causing the driver gear/dial to rub on the steel centre part (which is secured with those 2 internal screws). The plastic gear inside is toast but I’d be happy just removing it for now if this press fit weren’t rubbing and seizing. Currently the only way to use the machine is to loosen the lock but fully and allow the graduated metric ring to spin freely, which makes it hard making things to a dimension!

To cut to the chase, hows this come apart!!? I don’t want to force anything but my reason for stripping it, is that it’s already seized solid, and I can’t zero the dial even with the lock ring backed right off. This, it’s hard to tell what should and shouldn’t be forced.

Those two holes, are possibly tapped, and m3 screw fits but i’m sure it’s imperials as the grub screws were.

Its a vickers dual metric/imperial dial and it’s been jammed since I bought this lathe. No doubt one of the planet gears (more likely, the only planet gear) is damaged.

It wouldn’t be a problem as I don’t tend to use imperial (it’s a metric machine) but when I loosen the lock nut to zero the dial, it’s jammed solid, and I like to zero especially with these dials as the major and minor graduations are a bit odd!