Member postings for Jed Martens

I have one. I never use it. It's probably the only tool that I wish I hadn't bothered buying.

As others have said, it takes up a lot of vertical height. The issue isn't "daylight" in my case (SX3 mill) but the fact I have to crank the head all the way up to fit the indicator, and then all the way back down once I've finished with it. That's a pain in itself, but I have little confidence that alignment is maintained over that much vertical head travel.

I just use a DTI. Which I find frustrating much of the time, but it works and involves little head travel.

Jed

I gave it a go and it worked well (sample size of one). I just need to remember to allow a little more excess stock, as you effectively face four of the surfaces twice.

I didn't break out the surface plate to check accuracy, but just judging by how consistent and tight the parallels were as I rotated the part, it's at least as good as other methods I've tried. 

Edited By Jed Martens on 28/08/2020 20:45:32

Ha, I watched that video last night and thought "I'm so going to try that!"

Squaring stock on the mill today, didn't leave enough excess material when band-sawing, so had to do it the old way.

Ah well, there's always tomorrow...

There is a DIY Magnetic DRO thread that shows a number of approaches to mounting the tape

**LINK**

In my case, I made an aluminium carrier, while others have attached the tape directly to the machine with good results.

Here's a piccy of the back of the apron of my GH600...

You can clearly see the half-nut, which raises when you engage the threading lever. I can't think how the lead-screw could still be turning, and the threading lever engaged, yet the saddle doesn't move.

Are you positive that the lead screw is turning when the threading lever is engaged? Perhaps the lead screw sheer pin has snapped, but a bit of friction is causing the lead screw to turn. Until you place a load on it...

Daniel and Lee, thanks for that information, I'm off to read about oils

What oil are you using Lee? I think I'm just going to buy some from Warco, but I'm open to other suggestions

Hi guys, what oil are you using in the gearboxes?

Prompted by Triumphboy, I've taken the left-hand panel off to have a closer look for leaks. Since I'm new to this, and the machine is often covered in chips and cutting oil, it's possible that I've missed some. There is some evidence that a bit of oil has collected at the front left of the chip tray, but it isn't obvious where it might have come from. I think I'll top everything up and run the machine for a bit to see what happens.

Clearly I don't have a leak issue like Triumphboy though, I think that would have jumped out.

Diy Addict, by the nature of forums, all you're going to find in this thread is people discussing issues. It certainly doesn't represent the hundreds of hours I've spent making stuff with this machine. I really enjoy using it, and I'm glad I bought it.

Edited By Jed Martens on 16/06/2020 08:22:50

Thanks for the replies, I should have provided a little background. My wife operates a (very) small microbrewery. Years ago I built a semi-automatic bottle filling machine. This uses load-cells to detect fill-level, solenoid valves to stop/start the flow of beer to the filling heads, and peristaltic pumps (driven by stepper motors) to dose each bottle with priming sugar and bottling yeast.

The machine has 4 filling heads, but my wife normally only runs it with two heads operating, as she is still manually capping each bottle. So capping is the bottle-neck (pun intended).

The wee hand-held cappers are great for a batch of home-brew, but something less manual would help a lot in this case.

Regarding the speed when using a geared motor, as long as the capping operation is faster than the filling operation (around 15s) then it will be fine.

The suggestion of using windscreen wiper motors is very interesting. It essentially has the gearbox built in. A quick google showed that some claim to deliver 40Nm of torque, which should be plenty. Are these kind of motors reversible?

To those saying "use pneumatics" I have to say I agree with you! But I'd like to investigate the electro-mechanical options first, as the existing machine already uses steppers and relays and such.

Jed

I'm a "latest posts" kind of guy...

But I guess it depends on how often you visit. I check in a couple of times a day, so it's unlikely that something of interest will slip off the first "latest posts" page before I see it.If you visit less often, it might make sense to go to the section that interests you.

Hydraulics are even further out of my comfort zone than pneumatics! The long-term aim here would be to introduce a degree of automation. It's easy enough to control a stepper, and I can almost see how it could be approached with a pneumatic cylinder. But I wouldn't know where to start with a hydraulic system...

OK, something a little different for a Friday evening...

I've been reading here about capping beer bottles using a pneumatic cylinder...

pneumatic beer bottle capper

To give you an idea of the kind of thing being used to do this...

It is stated that the force required is "314 pounds" (100 PSI acting on a 2" bore cylinder). I'll take this as being 142kgf, or ~1400N.

All well and good, but I have no experience with pneumatics and no air compressor. I'm wondering if some electro-mechanical contrivance might work?

Consider a stepper motor generating 1Nm of torque (there may be much better motors for this job, but I've only ever played with steppers). A module 1 20 tooth spur gear mounted to this (driving a rack, for example), would generate a force of 100N, as the edge of the gear is 0.01m from the centre (length x force = torque).

This isn't enough, but we can of course use gears to reduce the rpm but increase the torque. A 14:1 gearbox would get us there.

I think the reduction in RPM is ok. The capper does not need to actuate very quickly, and provided the stepper can deliver maximum torque at 60rpm (datasheets I've looked at suggest this is ok) then I think the operation could be completed in a few seconds.

I'm pretty new to this - are there any obvious errors in my thinking above? What I don't have a feel for is whether small module 1 gears can be expected to carry these kinds of forces. Larger gears would be probably result in a solution that was too large (compared to the pneumatic cylinders anyway, which are probably the sensible way of tackling this...). Also, I would guess a 14:1 reduction would need a 2-stage gearbox...

Jed

Apologies, I may have the terminology wrong here, but I'll do my best The GH600 has a single powered shaft / leadscrew. For threading, the half-nut engages with the thread on the leadscrew to drive the carriage. For power-feed, there is a long slot milled in the lead-screw, which a key engages with.

The apron is easy to remove - I had to tackle that when fixing the saddle lock. From memory there are 4 bolts that go through the the top of the apron - remove those (and have some support underneath the apron so it doesn't drop on the floor) and you're done.

edit : this photo shows two of the blots. The top right of the three bolts (removed in this photo) is for the saddle lock. The other two secure the apron. There are a matching pair on the other end.

Jed

Edited By Jed Martens on 08/06/2020 15:47:21

The phone has a soft silicon case, which friction fits into the holder. It's a nice fit and works well, but to be clear, the bike is for indoor training only, I wouldn't take this out on the road

@Sam thanks for that. I was rotating the photo in windows (right click, rotate clockwise or counter-clockwise). I assume this just changes the metadata for the photo, rather than the pixel data, and the forum software ignores the metadata. I'll try doing a proper rotate next time(in paint I guess, I don't have photoshop).

Edited By Jed Martens on 08/06/2020 10:08:26

Continuing with this project...

I've put together my own DRO display, based around a 10" touch-screen and a Raspberry pi...

Starting from bottom left, there are 4 DB9 connectors that go to the scales. The red PCBs on the left are the RS485 differential signal converters. The output from those goes to the PCB at the top of the box, which is an FPGA card that does all the heavy lifting of quadrature decoding, counting, etc. It conveys the axis data via SPI to the Raspberry Pi (centre). This drives the display/touch-screen, runs the GUI, and has an Ethernet connection to the outside world. The board to the left of the Pi is touchscreen driver. The PSU is on the right.

Here's the case from the outside. I made it from aluminium, at just the right size to fit the screen...

I've started playing around with the GUI. Here's an example of one idea, where a bolt hole circle is plotted graphically.The wee cross-hair moves as you move the table, the plotted holes stay where they are.

I've separated Z axis and quill (which I've labelled Q, but I have no idea if that is correct - what is the quill position normally called?) and plan to allow them to be optionally summed together. 

Edited By Jed Martens on 07/06/2020 17:08:28

Edited By Jed Martens on 07/06/2020 17:13:53

@Tim Stevens - that sounds very sensible.

To complete this exercise in threading, I made 3 different fixings for this little project. This was thrown together "free hand" with whatever bits I had to hand...

The parts...

assembled...

Installed...

Apologies that the last photo is rotated. I can't seem to change it however much I pre-rotate the photo before uploading.

Anyway, it attaches to the end of my aero-bars on my bike to hold my phone...

I watched it last night. I'm very much a novice, and Adam very much is not, but my eyebrows were raised the entire time. He does address the obvious concern, but only by saying that manufacturer assures him it is ok. And also he isn't taking it anywhere near the 500lb maximum load.

My thoughts were to find some other method of mounting it to the lathe and mill. It looks super-useful for those large chucks and vices. But clamped into a tool holder with a couple of set screws?

Finished part, thanks all...

Gentlemen, thank you very much for such comprehensive and prompt advise. It has been digested and acted upon...

The setup...

the result...

This was still less then ideal, as I don't have any means of cutting a groove for the gullet, instead of using my parting tool. And I only have a big chunky dead centre. If I do more of this I'll be looking at some grooving tools and smaller centres. But it worked with what I had to had - thanks again.

Jed

I appreciate this is a common topic. I've read over many threads but I'm still messing up in the same way. Allow me to describe things in detail, and hopefully the answer is obvious to those with more experience...

I want to make a fixing/bolt with 25mm of M6 thread on one end, a shoulder, and a knurled knob on the other. The material is 303 stainless, from a 20mm round bar. I'm using a full profile 1mm pitch threading insert, and a fresh edge at that.

I start by turning down 25mm of bar to a shade under 6mm...

I then use a parting blade to cut a gutter on the left. I also add a chamfer on the right end of the rod.

Running at 80rpm (as fast as I dare) I cut the thread, taking 0.1mm off the diameter each time (0.05mm DOC). I use cutting fluid. The insert peels off a clean chip. Note that I am plunging straight in, not using the compound at an angle.

On two attempts, after around 7 or 8 passes, this happens...

In some ways it isn't surprising, as 25mm is a lot of stick-out for a 6mm rod, and the gutter creates an obvious point of weakness. But I'm still surprised that ~4mm of stainless can be snapped by the cutting force of that tiny little triangle on the end of the cutting insert. It occurred to me that tail support would help, but I can't get my centre and threading insert to occupy the same position in space at the same time.

After the part broke, I examined the cutting insert under a microscope, and the edge looks pristine, so I don't think the tool has snagged or degraded.

I appreciate that this would best be done with an M6 die, but I'm practising my single point threading. Am I making a basic mistake here? Or is thread-cutting long thin bolts not generally possible?

Jed