CNCing about Part 4

Hello again :o)

Sometimes you think you have figured something out and then it goes and does something else which leaves you baffled...

I had a few options on what I could have done today and I finally decided to carry on playing with the CNC mill, after all its still new and exciting for me plus the more I use it, the more confident I am getting with it. Todays fun with a CC milling machine was to try and generate some roof trusses for a GW engine shed I posted about a few posts ago. Maurice has been brilliant and sent me a laser cut shed he made but sadly it lacks any interior. As I need the interior (more than the exterior) I needed to get something together, so I made a start on the roof trusses.

These were modelled up in Inventor and the G Code was generated. I have decided to make them out of 0.5mm thick plasticard as it means I can glue them easily to each other and the wooden laser cut kit. Its also a bit easier to machine (or so I thought)..

I used one of the 0.3mm milling cutters I had and off it went, merrily profiling the trusses...

This is the result of today's efforts. The top one was the first attempt and as you can see I got the Z axis datum wrong and the cutter didn't cut deep enough. This was quickly corrected and the next four came out really well. Annoyingly though this is where it went downhill, the bottom truss in the photo is the result of what happened. Initially I thought it might be the cutter going blunt, picking up melted plastic, then braking but this is where is went weird. I replaced the cutter with a brand new one and it started doing the same, the plastic started to melt on the cutter and the cutter started to bend before eventually breaking. I then tried another (new) cutter and replaced the plastic with a different sheet, and guess what, it did it again! Strange as the feedrate and the spindle speed haven't changed.
OK, so I gave up on the trusses for today and tried to machine some more gears but once again it ended in the cutter breaking.

Maybe its the cheap Chinese cutters I am using? Maybe its the cheap plastic I got off eBay? Maybe its the ambient temp or something equally weird? Its time to have a rethink...

Julia.

CNCing about Part 3

Hello.

I manged to spend a little more time on the CNC mill today, mainly to experiment with a few things.

Thanks to Paul and Alan who replied with regards to my previous post offering advice so I had another go...

The two gears on the left are a result of mainly changing the cutting depth of the cutter from 0.75mm to 0.3mm and reducing the feedrate slightly too. The gear on the right is the result of adding a 0.1mm backlash offset to the machine through the software and the result was strange looking gear indeed. The results are lots better than the previous attempt but I feel there is still some improvements that can be made. Contrary to my previous post I now don't think the backlash of the mill is a big problem as I first thought.

When I was watching the cutter profiling the gear I noticed that for the first few passes the cutter was slightly deflecting but as the program carried on and the cutter traversed deeper into the material the deflection reduced.

The length of the cutting bit is around 6-7mm so I might try to pick up a 0.4mm cutter which is a bit shorter and this I think will make it better.

The thing is though, I think I now have a pair of useable gears so I might try them out in an engine...

Julia.

P.S. Boring post I know but things will liven up soon...!

CNCing About Part 2

Hello.

Things dont always go according to plan. Below is a good example of my imagination overwhelming my abilities (or should that be the abilities of machines)...

 One thing I wanted to try out was to see if it was possible to machine gears using the CNC mill. In my head it made sense, I had the ability to draw one, generate the G Code, and machine it, so why not? I duly generated a 3D model of a 0.3mod 22t gear which is one I need for a future engine build. This was then put through the machine G Code generator which promptly created 2700 lines of G Code. The smallest diameter was just over 0.3mm so a 0.3mm diameter end mill was purchased, along with some 1.5mm thick PTFE sheet. Everything was then loaded into the machine and the start button was pressed....

Everything seemed to go well. The cutter machined the PTFE without a hitch where I was honestly expecting it to break under the loads. The whole program ran in just over 6 mins and then it was time to remove the gear...

As you hopefully can see from the above picture the gear hasn't come out that well. Certainly not as good as I expected, especially considering how well it apparently machined. The gear profile isnt anywhere near as well defined as the model, even after an attempt to clean it up a little with a steel wire brush.



This leaves me with a little dilemma. I was really hoping to have the ability to produce my own gears, especially 0.3mod as its the most common size I use. Now, I am thinking the problem could be one of two things. Firstly am I bordering on the backlash of the machine which is affecting how much the machine is actually traveling? The mill doesnt have any positional feedback so its reliant upon the step motor revolutions to position the bed correctly and there is definitely no anti-backlash devices fitted. The second could be the end mill, I mean its 0.3mm diameter which is small! There is a chance it could have been distorting and flexing or similar during machining but I feel this is unlikely. Mainly because the feedrate was low, the spindle speed was high, and the material is relatively soft.
So, what could the problem be? At the moment I dont know and therefore dont really have an answer. Has anyone else got any thoughts?








Julia.

Some bits and bobs worth mentioning

Me again :o)

Just a post to catch up with bits and bobs I am working on and things that might be of interest to some people. Firstly a couple of bits for the 2mm Scale Association...

1. Farish Conversions

 All the design work for a method of converting Farish engines to 2mm Finescale has been completed for the first engine (the Jinty). If everything goes to plan, these will be available to members at this years AGM where more information on the conversions will be available too.

  2. Farish Standard Class 4 Replacement Chassis

The design of the chassis is progressing slowly as the design of the original chassis is quite a bit different from the new style of chassis. I am currently getting my head around the valvegear to produce am etch to replace the original...

The last two are just some things worth mentioning but not connected with the Association...

3. Peckett Chassis

I am going to try something out with regards to the chassis and CNC mill something out instead of relying on an etched one.

It still needs lots of work, especially with the gearing as I can produce a gear ratio from 28:1 to 138:1 for this engine. The plan is to produce some sort of split solid chassis.

4. GWR Engine Shed

By request Osborns Models are working on a laser cut large GWR style engine shed and progress has been great.

I have a (cunning) plan for one of these and I cannot wait to get my hands on one.

Julia :o)

P.S. If I am posting too much then let me know....

SVR Autumn Gala 2014

Hello :o)

For the past day and a bit I have had the pleasure of spending it at the Severn Valley Railways Autumn Steam Gala with the company of Andy H. We went last year and it was amazing to see steam engines operating in the dark so this year was one of those 'not to miss' events.

I decided to travel up on the Friday straight from work but it seems the traffic conspired against me and so I didn't arrive at Kidderminster until 6.30pm, a whole 2 1/2 hours later than expected, but once I was parked up I could then enjoy the weekend.

Nighttime photography has always alluded me, especially moving things like trains so as last years photos were admittedly a bit of a nightmare I tried to read up on how it should be done. Now I will be honest and say that my photography skills leave lots to be desired and I have always worked to the  thought of 'if I take enough photos I am bound to get one or two good ones' and this year it seems I have had a little more luck, here are some of my favs...

Ok, so they aren't going to win any awards but I am happy with them and they are a definite improvement on last years! Sad to say though, these people were more prevalent this year...

...and as you can see it was very hard, almost impossible to take photos of some things. There were times when they came and just set up their cameras in front of me while I was trying to take photos, and to me some were quite rude to other members of the public. I know I was just trying to do the same but I try to be as considerate as possible to others. Anyway, whinge over...

The Saturday was nice too...

  A 4f amongst the flowers, a timeless scene.

I think there is a leak there.

The fireman said to me "when you are filling at 5000l/min you aren't worried about a 5l/min leak"

The relief crew poised, ready for action

Finally my favorite photo of the (205!) I took...

But how stereotypical! (Its on the M7 btw).

For those who haven't been to such an event I would thoroughly recommend it, seeing steam engines and trains running in the dark is a whole different world, its so atmospheric (hence why my layout Highclere can be run in the dark). I will be back in 2015 and fingers crossed my photography might be slightly better then too.....

Julia :o)

EDIT:

I took only one video, it was taken at around 4am on Saturday so apologies in advance if the quality is a bit poor...

:o)

More Weathering

Hello.

More photos from the painting and weathering genius that is Steve T. This time its the turn of my GW Class 52xx...

This was a Worsely Works etched kit with a scratchbuilt chassis. Detailed, painted, and transfers by my fair hands, then passed onto Steve for the finishing touches. This is the second engine to be weathered by Steve, the first being my Farish Jinty. Please bear in mind that the photos have been cropped but thats all, other than that they are camera fresh.

(A very happy)
Julia :o)

Things this weekend

Hello again :o)

Well, this weekend was a busy one! Two shows over two days with lots of people to talk to and lots of things to look at and do. Sunday evening I looked (and felt) like I had been to some sort of festival...

Saturday was spent at the Swindon 'Steam' festival at the Swindon Steam museum. Its the 3rd year I have done a demo there and it never fails to impress me on the venue, content, and general atmosphere of the place. I mean, how many model railway shows are there each year where the stands and layouts are mixed in with the Great Westerns finest steam locomotives, its such a mecca for people like myself.

I managed to get some modelling done too in the form of putting together my recently CNC milled chassis side frames for the PECO collets I have. It was fairly straight forward as the bits were already ready from the previous attempt so all I needed to do was swap them over to the new frames. I am sure to post about them sometime in the future. I was a little saddened by the performance of some of my engines which had the opportunity to run on Mick S ever excellent Wansbeck Road layout. Its hard not to compare them to Micks and John Gs engines which I know it not a good thing to do. They are in a different league to my modelling abilities and their modelling never ceases to impress me. Its good to have something to aspire to though, and hopefully one-day my modelling will be held in just as much high regard as theirs.

Sunday was spent the the N Gauge show (TINGS) where once again I spent an enjoyable day mingling with other members of the public talking to people and marvelling at all the nice bits and bobs on display. The highlights for me at the show were the following..

• B&H Enterprises 3D printed streamlined railcar, fortunately not the later one like my 'Elvis' but the earlier version. It was very well printed and has been duly added to my shopping list.
• Osborns models laser cuts buildings and things. They looked really well done and I am looking forward to purchasing some in the near future.
• Brixham Bay N Gauge layout, absolutely superb modelling, the buildings were amazing and the whole layout was presented really well. everything was nicely finished and toned down. Definitely the best layout there in my opinion.

The last thing that I feel is worth mentioning is the 3D printed bits from DJM. To me, the display and representations of future models was shockingly bad. So much so that even the guy on the stand seemed embarrassed about them when I spoke to him. NOT a good advert for someone who is trying to gain a foothold into the market and the total opposite to all the hype I have heard about.

Overall I had a brilliant weekend and from what I have heard, it sounds like I made the right choices of what to go to as well.

Julia :o)

CNCing About.... Part 1

Hello :o)

A few years ago I went into a sort of partnership with a guy called Steve from the Oxford 2mm group. The deal was that he provided the milling machine in the form of a Proxxon MF70 and I would supply the CNC conversion kit. I purchased a conversion kit from a company called USOVO and the mill was duly converted by Steve. It was then passed onto me to finish off the conversion and get the thing working.

Roll on a couple of years and after not touching it I decided to get it out of the cupboard and try to get it working as it seemed too good to hide away unused. This is where another guy called Robert stepped in as I just couldnt get my head around the electrical connections and configuring the Mach3 control software. Robert took the mill and promptly got it working in about an hour and it was then back to me to finalise a few settings and tweak it until it was happy.

Anyway, its all up and working now and I am one happy bunny. Even better I found a plugin for Autodesk inventor which creates G Code based on my 3D models. It even does a nice little preview so I can check to see if everything works how it should.

Even with this preview, it still took a bit of 'tweaking' to get the machine cutting right though..

Eventually it all came together..

And now I have four chassis sideframes for my PECO 22xx collett engines on my 'to do' list..

Thank you goes to Steve and Robert in helping get the machine to this stage. The trouble is now what can I do with it next....




Julia :o)

All Change

Hello.

Well, its been a long time since I have posted on this blog but thats about to change...

For various reasons, all of which I am not going to go into publicly, I have decided not to continue posting details of my modelling on RMWeb but instead focus my posting on this blog instead. As I said, I am not going to go into details on my reasons for this but instead if anyone is mildly interested then request that you contact me directly where I will explain in more detail.

So, if you are interested (for some weird reason) in what I am doing, then please bookmark this blog and you will be able to keep track of what I have been upto.

Regards.

Julia :o)