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Contacts info for a get together

Posted by vizion 
Re: Contacts info for a get together
July 30, 2012 04:56AM
Hamish - thanks for the comments. I know Maplin well, but don't like mail order until I reach their "post free" threshold - although with things like the little PC connectors, that soon happens... Wouldn't mind finding a better online source but it hasn't been a priority to date.

As for Z couplers - I bought a kit of printed parts and am using the clamp-on couplers that came with that, combined with a bit of plastic tube on the stepper shaft. However, it's a bit of a mechanical monstrosity and I had been planning to turn up some couplers out of brass. Thread one end to screw on to the threaded rod, plus grub screw to lock it all solid, and then chuck by the rod to bore out the other end to fit the stepper shaft so that the holes were accurately coaxial. Or maybe turn down the ends of the threaded rods to stepper shaft size and fit to a straight coupler. Not sure yet - might depend on what's in the scrap box of odd metal stubs! I cleaned up the ends of all my threaded rods and chamfered them in the lathe, and the stainless seemed to turn fairly easily.Having metal-working machines in the workshop, my mind tends to run along fixes based on those rather than printing. Either way, I am looking to make sure that the threaded rods are accurately coaxial with the stepper shafts to avoid wobble from that source. The other question is whether or not the shaft is properly lined up with the nuts, and I am hoping that this is accurate as both sets of parts which define the spacing came from the same source.

I shall also look for the Nophead coupler design, though - presumably found via his blog?

- Brian
Re: Contacts info for a get together
July 30, 2012 05:41AM
Re: Contacts info for a get together
July 30, 2012 06:17AM

- Brian
Re: Contacts info for a get together
July 30, 2012 04:13PM
Looks like you had a nice turnout in Exeter on Sat, good stuff!

Brian, I got my z axis couplers from Nophead. If I was printing them I might try clear plastic, so you might see any gap opening up betwen the stepper & the threaded rod. Guessing the bit-of-monstrosity clamp on couplers are these:

ali couplers

Re: Contacts info for a get together
July 31, 2012 05:40AM
I've probably gone and put my big foot in it, but I'd better 'fess up....

I think I do have Nophead-style Z-couplers - two-part, identical apart from nut retainers, and different size holes at each end. Fitted over a short length of plastic tube on the stepper shaft. So the fact that the threaded rods wobble as they rotate at the stepper end is probably down to either poor printing, or a complete lack of dexterity in fitting. In the absence of other evidence, the guilty finger probably points at me! I'll take them apart and refit with a bit more care. Those joints haven't been disturbed since I first put the machine together a whole 4 months or so ago, and I probably didn't realise the significance at that time. Having a machine that printed at all seemed like a minor miracle.

In the meantime, I have managed to tune my Sprinter PID temp parameters. I found that a useful trick was to use PuTTY to issue M commands for temp setting and monitoring; it's then easy to import the log file with temps into Excel for graphing. Heater temp overshoots by about 8C at first and then takes a minute or so to settle, but once there it only varies by +-1C over long periods. Better than the nearly +-10C that it was doing before! Took an evening to get it sorted, and was down to trial and error in the end, but it's done now. I did consider using Marlin with its PID autotune to grab the parameters and retrofit into Sprinter but looking at the code, it looks as if they use different values. At least, reading the code gave me a bit of insight into how the various parameters affect the results. I shall see what it's like when actually printing but I can't believe that the melting process takes a lot of heat out of the block given the small amount that is passing through.
Re: Contacts info for a get together
July 31, 2012 05:59AM
Hi Nealeb,

I dont think a problem with your Z couplers is that unusual, I have the same type on my prusa and although they are fine now i found that the type and wall thickness of the rubber pipe is a critical factor. When i first put the machine together the Z rods actually dropped off the stepper shafts even though it was done up tightly and appeared to be a firm fit. So I switched from PVC hose to Silicon hose- tempting fate here but so far ( 6 weeks or so?) no problems- and very smooth operation even though my motors are bolted down solidly.

Looks like you all had a great meet up Exeter sorry to have missed it but hope to get to the next one.

Ref your Sprinter /marlin PID issues, Rob may be able to advise here? he did a brilliant job of swopping my system over to Marlin for which I really can't thank him enough!

looking forward to the next meet up


Using ABS Prusa Mendel from Indieflow (eMaker website) with Pronterface and slic3r (0.9.2) . Printing with 3mm PLA through home constructed J Head hotend and Wade Herring bone Geared Extruder. Sanguinolulu board running Marlin
Re: Contacts info for a get together
July 31, 2012 06:32AM
Good to hear you're on the right track re z-couplers Brian.

It appears that people suffer various teething problems with z-couplers of any printed design - one of my nophead ones dropped off a few days after first assembly, but after degreasing all associated metal and plastic (with ipa or similar), they've both remained in place ever since, (6 months+) and that's with the original PVC tube as supplied by nophead.

At the end of the day, what ever works is the best solution. (Erm... speaking of which, albeit a slight digression - keep an eye out for the landing of Mars Science Laboratory aka 'Curiosity' on Mars next Monday morning:
project homepage: http://www.nasa.gov/mission_pages/msl/index.html
Check out the arrival / landing sequence!
If they pull it off, it'll be the first time the entire system has been consecutively functionally tested. Now that's what I call engineering on the edge - awesome stuff! Certainly put's z-couplers probs into perspective eh?)

Right, engineering excitement over, back to the real world...

BTW, thanks for the insight into PID tuning - something I've yet to play with.

- Hamish

Edited 1 time(s). Last edit at 08/01/2012 04:14AM by hairykiwi.
Re: Contacts info for a get together
July 31, 2012 06:51AM
Yes I had one side that would move down a small amount each build while the other side was stable. It didn't matter how tight I made it. Degreasing the motor shaft fixed it.

The opensad file on Thingiverse is parametric so you can measure the OD of the tubing after it is fitted and print one to fit better. It does need to be a bit undersized to grip well enough. Motors at the bottom is a much better arrangement.

Re: Contacts info for a get together
July 31, 2012 11:24AM
Some progress...

When I took off the couplers, I found that the clear PVC tube that I was using must have been a little oversized and it had squeezed out a couple of "ears" that were sandwiched between the two halves of the coupler and that were preventing the coupler tightening symmetrically. I took it all apart, shaved off the ears, and reassembled, carefully tightening so that the gaps between halves were symmetrical and constant up and down. It's much better now, with virtually no visible wobble. Now need to look for other sources of poor print quality - mostly "ripples" in the sides of tower-shaped prints. Removing Z wobble has helped but not removed this as the regular ripples have gone and left smaller random ripples! Possibly vibration in the rather unbraced Prusa structure; printed timing belt pulleys aren't entirely concentric, etc.

Still, we are getting theresmiling smiley
Re: Contacts info for a get together
July 31, 2012 12:28PM
Yes "Curiosity " 6th Aug, I've got reminder on my phonethumbs up

Using ABS Prusa Mendel from Indieflow (eMaker website) with Pronterface and slic3r (0.9.2) . Printing with 3mm PLA through home constructed J Head hotend and Wade Herring bone Geared Extruder. Sanguinolulu board running Marlin
Re: Contacts info for a get together
August 01, 2012 02:48AM

Thanks Stuart for the meet up, it was good to see more Repapers moving forward so well with their builds, Handy to have someone with a vested interest in progressing repraping, and a easy access venue.

Marlin is definitely worth having a play with, i didn’t know about the varying PID parameters though, I assumed as originally marlin was derived from Sprinter they would be the same, i will have a look when i get chance, always handy to understand these things


Join us at a regular West of England RepRap User Group event
For details, visit tiny.cc/woereprap or tiny.cc/woerug
Re: Contacts info for a get together
August 01, 2012 06:09AM
I've just checked my couplers (I'm also using Nopheads design) and it appears I've had the same issue as Nealeb - The tube is getting squashed and slightly deformed. I'm printing some new ones out now, making the gap slightly larger. Will let you know how that goes.

Been looking through Marlin as was suggested as well, not yet got my printers running it, but should have news to report on that front by the end of the week.

As was also discussed, but that I'm throwing out to the rest of you who weren't able to attend - I'm more than happy to host meetings at my workshop on a monthly basis, providing of course there is the interest in them. (It doesn't really effect me one way or the other - Saturdays are a work day for me just as any other day, so I'll be there regardless.) So the question is, would people be interested?
Re: Contacts info for a get together
August 01, 2012 04:01PM
Stewart - in my case, it looked as if there had been some creep in the plastic tubes into the gaps between coupler halves. I just trimmed these "ears" back, and I was then able to fit the original couplers and get even spacing between halves for their whole length, implying that the centres of the two ends should have been coaxial. Seemed to work OK for me. I didn't want to print new couplers as my Prusa isn't giving quite good enough print quality yet and this was a quick fix! Enough to reveal the next round of tuning needs...

PID tuning parameters - my comments were based on a quick look at the code as I was thinking of retrofitting the Marlin autotune code back into Sprinter. However, I might well be wrong. I also thought about running Marlin, using its autotune to get the parameters, and then putting those back into Sprinter - it's easy enough to download firmware, after all, and there's nothing to say that you can't switch like that. In the end, manual tuning wasn't that arduous and I'm pleased with the result. Switching to Marlin might be a good idea but I'm trying not to change too many things at once.

Back to the main theme of this thread - I can make Exeter easily enough especially by motorbike (favoured form of transport, especially with holiday traffic on the A381!) but I can't carry a Prusa on that. Monthly meeting might be a bit too often for me, but every couple of months might be good to swap notes.
Re: Contacts info for a get together
August 01, 2012 06:39PM
Just into August so I thought I would remind everyone that there is a planned RAPREP cool smiley Meeting which is taking place on SUNDAY 26 AUGUST at NEWPORT, South Wales, about 15 minutes from the seven bridge

Bring your machines, All REPRAP 3D printer fans are welcome 11am to 6pm or so. Just a reminder today, more details later

Email me if you can come, I look forward to seeing the usual regular faces!

Paul smileys with beer

At the same location BUT on SATURDAY 25 AUGUST, my Engineering Society Club is having an OPEN DAY, if you have children and/or Grandchildren then they can have a fun day out riding steam trains etc., lots going on, including an Engineering Exhibition, join us if you live within driving distance. Email me for more details
Re: Contacts info for a get together
August 02, 2012 01:48AM
Paul2d3d Wrote:

> Email me if you can come, I look forward to seeing
> the usual regular faces!


Not an email, but to let you & the rest of 'the gang' know yes I intend to be there on the 26th.
Looking forward to it.

Re: Contacts info for a get together
August 02, 2012 09:10AM
Hi Paul,

I’m hoping to make the 26th,

Children or Grandchildren only! What about those of us who are very immature!

Although I suspect one trip to Newport is sufficient for a weekend

Looking forward to it, I had a magical moment the other night,
I finally printed my first replacement extruder (and herringbone gears) Monday evening
Few first layer issues but I think my tape was dying, just in the process of building it up at work, but it looks like it should work well
So hopefully I will be well into printing my new design by the end of august


Join us at a regular West of England RepRap User Group event
For details, visit tiny.cc/woereprap or tiny.cc/woerug
Thanks to Stuart for hosting a very helpful and enjoyable day in Exeter at the end of July.
I was near completion of my first reprap, which is now operational and the chance to meet and talk about it enabled me to answer some important questions. I'm looking forward to coming to the next meet.

Once the build was complete, the various Richrap resources enabled me to get up and running - so many thanks to him for all of that, especially 'slic3er is nicer' which makes everything so clear.

I have made some simple objects now - the dimensions/mechanics/axes seem to be ok but I can only print very slowly (10 in the speed setting) and am frustrated by stray loops and random problems with extrusion which I can't seem to figure out. I'm using a jhead 0.4 nozzle (MkIV). I've tried varying the temperature - too high and the extrusion stops, presumably because of melting higher up the tube, too low and it just stops. It seems impossible to get one clean print that doesn't have a section that is haywire.

Early days for me yet, and I hope to pick up more tips in a couple of weeks but if anyone can offer any advice in the meantime I would be very grateful.

Re: Contacts info for a get together
August 08, 2012 09:30AM
Hi Mortimer,

I can't spend too long helping right this moment, sorry, but we'll get started... Even if I'm not about to answer your reply to this, it should help someone else help you.

Is the knurled bolt clean after extruding some material, or is it chewing your filament and getting clogged?

Which extruder body are you using? They generally all work fine, but 'Greg's accessible Wade' is easier to inspect/clean loose bits from the knurled bolt when it does happen.)

With your nozzle set to 185 - 205 for PLA (other's will advise a temp range for ABS) can you push the filament through with 'moderate' ease by hand? There is a very small chance your hotend thermistor (temp sensor) is damaged, so it could be your hotend is not at the temp you're expecting it to be.

Are you cooling the top (cool part) of the hot end with a small fan? That helps a lot.

If you have a dropbox.com account or similar you could very easily share some images of what you have managed to print - and perhaps of your machine/hotend. (Click here to join and we both get an extra 500MB free storage.)


Hi Hamish

Thanks for coming back to me - I've set up the Dropbox account as suggested and will put some pictures in it later.

I think a little bit of chewing up is going on with the bolt - the parts came from the infamous 'thereprapkitstore' and I'm not quite sure of the derivation of the extruder body - it doesn't look quite like most of the others I've seen. It was quite a job to get it to extrude in the first place. I have found the extrusion calibration very inconsistent - following Richrap's advice to extrude 30mm slowly and measure the progress of the filament, it just isn't a smooth process, but not having played with these things before I wasn't sure what to expect.

When I push the filament firmly it will prompt some extrusion, but it isn't an easily continuous process.
I've no way of calibrating the thermistor, but I think it must be fairly close to reality - when off it reads close to room temperature and I've found a set temperature of 195 seems to get it basically working.

I'll get some pictures up soon, and hopefully tomorrow will have the time to try the fan on hot end tip.

Your advice is much appreciated, thanks,

Re: Contacts info for a get together
August 08, 2012 11:19AM
Hi again Mortimer,

That 'little bit of chewing' is enough to throw the calibration process out the window. Been there, done that winking smiley

The two springs on my Greg's accessible Wade are almost fully compressed for reliable operation: 8mm OD, 19 - 20 mm uncompressed / 13mm working compression. More compression (for PLA) is better, generally speaking. Rich will have more precise info for sure - and possibly also the different requirements for PLA and ABS.

>When I push the filament firmly it will prompt some extrusion, but it isn't an easily continuous process.
That sounds about right - certainly it's how I'd describe my experience with my Arcol hotend. (Which, BTW, is now running MUCH more reliably with the addition of a cool breeze from a 40mm fan running over its cold section - I get this running right from startup to prevent the possibility of shock cooling effects (others turn it on only after the first layer). On a related topic, check out nophead's blog for the startup g-code I'm using - he wrote about it here earlier this year - I highly rate this method for getting highly repeatable results from cold.)

Also, check your Extruder driver gear - mine started slipping on the stepper motor shaft after quite a few hours of operation. It can gives similar symptoms to a blocked nozzle.

I'll be away for a week from tomorrow, but no doubt if you put some pics up other people will chip in to try to help you out.

All the best,
Re: Contacts info for a get together
August 08, 2012 03:31PM

>I'll get some pictures up soon,
If you can a pic of your hobbed bolt might help. I had mine from the repRapKitstore, which clogged after a while. I replaced it with a deeper grooved one with improved results. The shallow grooved one I got back end of last year, RRKS may be supplying a different type now of course.

Re: Contacts info for a get together
August 08, 2012 04:00PM
Just as a point of comparison, my home-cut drive bolt was cut using an end-mill on a milling machine, and for simplicity I made eight teeth which are very sharp, and with a "driving" face at 90deg to the filament so there is less chance of it sliding back. As a result, there is a lot of space at the back of the teeth and although you might think that eight teeth is not enough to give a steady and reliable feed, in practice (at least with PLA which is all I have printed to date) it has turned out to work very well, including reliable and consistent retracting. I suspect that the commonly-found shallow teeth could easily suffer from clogging, especially during the initial setting-up stages where you are still getting things right and when you are more likely to be trying to drive a filament through a clogged or too-cold hot end. In my case, the hole in the bottom of the extruder wasn't quite lined up with the edge of the bolt so the filament tended to jam there and my nice sharp teeth cut wonderful shapes in it! But opening up the entry to the hole slightly cured that one.

Anyway, my vote is for fewer deeper teeth, rather than too many shallow teeth which is what might tend to happen with the usual hobbing technique.
Thanks for the replies - here are some pictures:

This is my extruder:

The instructions suggested using only two bolts at opposite corners. I've tried various combinations with or without springs. The springs supplied were so strong I was unable to fit them...

...and here is the bolt: [dl.dropbox.com]
which shows a certain amount of filament chewing. I wonder if it needs a wider bit of 'hobbing'?

Here are a couple of prints - some of them are fine in places, but haywire elsewhere and sometimes delaminated:

I've tried various levels of compression on the extruder, not quite sure what to do next, apart from fitting a fan.
Perhaps it's time to change or adjust the bolt?

Any suggestions very welcome, with thanks,

Re: Contacts info for a get together
August 09, 2012 06:44AM
Hi Mortimer,

Initial look says your Hobbled bolt is out of alignment with your filament,

At a guess, you looks like you may be struggling to remove washers from behind your gears to fix it,

Personally, and I’m aware I’m not the only user who has had issues with this
I’ve turned my bolt 180 to put the error in the other direction and allowed me to pack it with washers on the back, then i use a nylock in the gear to act as the head,

You may find you need a 1/2 washer on the gear side to clamp across the gear to stop the nut undoing its self
Your hobbling looks deep enough to me, the grinding looks although its from where the filament has been rubbing against the thread,

Give it a try and update us


Join us at a regular West of England RepRap User Group event
For details, visit tiny.cc/woereprap or tiny.cc/woerug
Hi Rob

I think you are right - I did have trouble getting it aligned, and it still is a bit to one side - the washer depth has been an issue.
I hadn't thought of reversing the bolt, that's a great idea and I'll give it a try.

Many thanks,

Re: Contacts info for a get together
August 09, 2012 03:03PM

Yes looks out of alignment. I had the same problem, sorted by the group at the first meeting I went to.
If its not too late when you remove the bolt photo it again anyway, the goove depth looks ok but 'U shape' on the ridges looks a little shallow, like my original rrks bolt, but not easy to tell from that pic.

Re: Contacts info for a get together
August 09, 2012 03:33PM
Hello all

Not far away from our meeting on SUNDAY 26th August in NEWPORT. South Wales

Only about 2mins off the M4 motorway and about 10/15mins from the seven bridges or about 5mins from the m50/m4 junction

Looking forward to seeing the regular group and meeting any people who are interested in the 3D printer. You will all be made welcome


Plenty of room for all of your 3D printers, looking forward to seeing what progress has been made and what parts have been printed

How about a STL file swap!

Food, tea and coffee etc. is sorted for us all


Many of the group have their machines fully working and other members are not far behind, how about FOUR to SIX of us starting a sub-group to setup a RepRap building project of a new item not yet built on a RepRap machine!!

Put your thinking caps on, let’s come up with a brilliant design of something that we can build!!!

I will do all the 2D and 3D drawings and check the functionally of the design plus make any metal parts (frames, bushes, spindles, gears etc.) we can share the make of the various RepRap parts between the group.

We will need an electronics person as almost all designs/parts etc. are controlled electronically and it would be nice to control our objects via the computer!! Just a thought

Anyway put your minds in gear and let’s see what we can come up with ?????

Hope you can all make it

Talk soon and don’t forget to send me your email address for instructions

Thanks for all the help at the end of last week to get my printer up and running.
I've now made my first successful/useful print:


...the richrap raspberry pi box with lugs.

Still some way to go with getting things completely stable, smooth and so on, but definitely on the right lines now.

The problem was indeed filament alignment - the bolts I was supplied with were catching on the extruder gear with the capped heads, pushing the bolt out of alignment and this was exaggerated by a warped gear. Replacing the bolts with smaller headed ones just enabled everything to align.

Re: Contacts info for a get together
August 27, 2012 01:48PM

Many thanks for organising yesterday's event, to your wife for preparing the great feast - and special thanks to the Newport Model Engineering Society for hosting us.

Many thank's for the invite to return too! Being as central as it is to the Southwest RUG region - and with such easy access just off the motorway, I'm definitely keen to meet in Newport on a semi-regular basis.

RepRap-wise it I really enjoyed the day. Especially for all the useful titbits of information that only seem to be surface when you get talking face-to-face with like minded people.

Here's a few links related to some of the things that came up in conversations:
A 'beat synthesizer' developed as an opensource project and printed on a RepRap.
For more information visit: onyx-ashanti.com

Calibration pieces Calibration 01 is for checking bed level and/or z-axis height is good. Calibration 02 is for checking volume of extruded material is correct for the first and subsequent few (4) layers; i.e. 02 is a layer-by-layer snapshot enabling (slic3r) settings to be considered at leisure, rather than trying to make an on-the-fly mental note of what, if any settings need adjusting - before each layer becomes obscured for good.

Sunglass.io - a platform for collaborating on 3D design - including editing, marking-up and showcasing. It has dropbox integration and compatibility with over 40 industry file formats. Features/FAQs Being touted as the 'google docs' for 3D.

3D software I'm using:
MoI3D - US $295. An absolutely fantastically intuitive user interface - written by the original author of Rhino. Native format is 3DM, exports to STL/SKP/IGES/STEP/AI/OBJ/3DS
Alibre - US $200. User interface nothing special, but reasonably powerful. Supports assemblies. Works well with in conjunction with MoI3D. Exports to STL/IGES/STEP, possibly others.

Other's I've played with and been impressed by:
Creo Elements/Direct Modeling Express 4.0 free, very powerful geometry manipulation. Only exports to VRML and STL.
Sculptris FREE - Awesome for freeform mesh modelling.
[www.powershape-e.com] A Delcam product (developed in Birminham, UK) with integrated tools for surface, solid, and mesh modelling/manipulation. Can create assemblies. Uses a voucher system to enable file export on a per model basis (approx £50 each model to unlimited industry file formats).

smileys with beer

Edit: Added link to calibration pieces

Edited 1 time(s). Last edit at 08/28/2012 05:08PM by hairykiwi.

Re: Contacts info for a get together
September 05, 2012 02:33AM
I'm thinking of organising a get-together in Swindon, Wiltshire on either 22nd or 23rd September. I'd need to book a hall for this so I need to check that this is,a suitable date first. It's got a kitchen so Chilli is still on the menu!

Anyone interested?

Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9
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