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Once upon a time...

Tuesday, 29 June 2010

Adding Axes

To start with, I have come to realise that other people refer to the bed as the Y-axis and the gantry as the X-axis. (No such confusion about the vertical axis which all agree is the Z-axis). To this end, I have gone and updated my previous posts.

I managed to get quite a bit of time in on the weekend in order to work on the X & Z axis drive systems. Today's story will be told with pictures:

I started with the X-axis drive system (pic 1) and mocked up the Z-axis location (pic 2) and the drive system (pic 3). This made me realise I needed to add spacers to the X-axis rails as the drive system need more space (pic 4):
Inkjet print head carriageX-axis mockupX-axis drive mockupX-axis rails raised

I then created a mounting plate for the Z-axis, and fitted the X-axis drive. As you can see from the pictures, this is pretty much as removed from the printer, but I cut down the cartridge holder to make a flat surface which could easily be attached to the Z-axis mounting place. I then realised that the (wide) mounting plate (pic 1 below) was fouling on the drive system so I made up a new narrower one as seen in the second pic below. Looking carefully this pic also shows that I had to notch the side of the gantry to get the stepper motor to clear.

The 3rd pic shows how I bent down the X-axis rail end stops to allow the rails to travel in both directions. This means that I could center the Z-axis on the rails. I guess this might come to haunt me in the future as it means I need clearance on both sides of the ScrapStrap, when working, but at least it is less clearance (breathing room) than single sided movement:
X-axis mounting mk1X-axis mounting mk2X-axis extended travel

The next step was to mount the Z-axis and it's drive mechanism. This bit was quite fiddly and changed along the way so I didn't take lots of pictures in the middle but did of the end result. Bottom line is that I stripped down another ink jet cartridge drive mechanism and used the stepper motor, drive belt, cut down cartidge holder and spring loaded belt tensioner. The most fiddly bit was to align all the elements so that the belt would grip properly.

The 1st picture shows how I used a single bolt at the bottom and two at the top. This would allow fine adjustment of the 'verticality' of the axis in the X-plane. The 2nd picture shows the initial mockup of the drive train.

The black bit that you can see in the 3rd picture is the cut down cartridge holder, while the bolts are there to attach this to the Z-axis.

Z-axis adjustableZ-axis drive 1Z-axis drive 2

These last two pictures show the X & Z-axes completed and mounted on the Gantry. there are two picutres to show the travel in the X and Z directions.

Gantry mockup 1Gantry mockup 2

In these pictures the Gantry is not yet mounted to the Y-axis base as I need to ensure that I get this perpendicular. I'm still debating how to ensure this and how accurate it needs to be.

There are 3-planes in which the perpendicularity needs to be ensured. For the X-plane of the Z-axis I have built some adjustment in the Z-axis mounting. The other 2 planes are:
  1. The X-axis in the Z-plane (i.e. the gantry tilting back and forth); and
  2. The Y-axis in the X-plane (i.e. the gantry tolting left to right).
Currently I am swayed towards fixing them in the place (i.e. no adjustment), but starting at one corner and measuring carfully before adding the next to get it as close as possible. Considering that the ScrapStrap is quite rough and ready anyway, this might be accurate enough.

Any comments????

Thursday, 24 June 2010

Belting the Bed (Y-Axis)

Not too much to report today after the mega progress on day one.

I had a little dig around the bins of printer parts I salvaged and managed to locate a decent looking stepper motor as well as belt and pulleys of the correct size.

Here's a pic of a couple of my bins (I have more):
Printer bits

I had to remove the original pulley from the stepper (hope I didn't damage it in the process) and file a flat on the shaft.

This was all pretty fiddly work as I had to figure out what to do and had to attempt some of the brackets multiple times to get them right. The pics below show the sequence of fitting the stepper, pulleys, belt and finally the bed:
x-axis undersideX-axis beltedBelt bracketBed and belt

That's all I got done for now, but I thought I would also show you the pics of the two inkjet print head carriages that I dug out and plan try to use for the X & Z axes. The motors are quite light so not sure if they can handle it, but what is nice is that they come with pulleys and belts. I guess only time will tell.
Inkjet print head carriage 1Inkjet print head carriage 2

Monday, 21 June 2010

ScrapStrap (a RepRap BootStrap AKA RepStrap)

For those reading I'm back!! a few days ago and wondering about the RepRap, here is a bit more information.

I'm not going to repeat what is available in the RepRap.org wiki, but will paraphrase as a quick introduction.

The RepRap is an open source project to create a self-replicating 3d-printer affordable for the masses. At it's simplest 3d-printer is the type of 'printer' which prints melted plastic into 3d shapes. The current incarnation is the Mendel. All of the plastic parts can be printed on another RepRap or similar, whereas the metal parts, electronics, motors and fixings have to be bought (these are known in the community as vitamins).

The problem lies when you don't have your own RepRap or ready access to one to print the parts for your first Mendel. This is when you have to build a bootstrap device (referred to as a RepStrap). This is a machine which can print in plastic like the RepRap/Mendel, but isn't self replicating. Almost every builder comes up with their own interpretation on this, with some users actually creating very sophisticated systems (see Hydraraptor for an interesting build).

Over the last 3 or 4 months I have been slowly acquiring all the bits to assemble a Mendel, with the plastic now being the main remaining part. I was temped to build an OverlapStrap as built by Giles Bathgate. This attempts to use the same 'vitamins' but with temporary replacement parts for the plastic items. While researching this and deciding what to do I realised that it was difficult to figure out the dimensions of the plastic parts using the drawings and Sketchup. When I posed some questions on the forum yesterday, I was reminded that the WolfStrap would be a good starting point.

The WolfStrap is a typical Gantry type CNC cartesian bot which can be simply made with DIY materials. Last night after dinner I decided to get started so made off into the garage. Looking at my collection of raw materials (I have lots and odds and sods as I am a bit of a DIY hoarder. I always think I can use something again), I came up with the following:
  • The name for my RepStrap - ScrapStrap (as it is made of scrap).
  • Two sets of drawer runners from an old flatpack filing cabinet.
  • A small sliding mechanism removed from an old Dell PC/Monitor stand. It was designed to allow the vertical height of the monitor to be adjusted.
  • The 'legs/base' of an old chipboard occassional table (This is type where two rectangular wooden sections with slots it slide into each other to form a +).
  • A small piece of lightweight caravan worktop
These pictures show the above materials:
PhotobucketBasebed material

Dell monitor mechanism is quite intriguing as it comprises a set of mini drawer slides, some bracketry and a spring, string, pully and friction brake mechanism design to overcome the weight of the monitor. It even has 15" and 17" markings imprinted for calibration. I have some more detailed pictures here:
Dell monitor railDell monitor railDell monitor railDell monitor rail

The last two of these are with the weight mechanism removed. I couldn't see the benefit for a RepStrap on which the extruder should be quite light. Probably useful for a mil, but then the 90mm travel will become a limiting factor.

According to the forums, the highest Mendel part is around 30mm, so the 90mm travel that this part will give me should be ample.

The build

I layed the one chipboard base flat and fitted one of the draw rails on the face but right against the edge so that it extends backwards. Making sure it was straight relative to the edge of the base I screwed it down and then fitted the second rail to the opposite side. For this one I fitted one screw then carefully measured to make sure it was parallel to the first and fitted a second screw to lock it in place.

The rails I used have tabs which could be used for locating the deck/base (Y-axis), so I then took the piece of countertop, carefully measured and cut it to fit between the tabs. Before screwing it down I double checked that it moved freely back and forth to ensure that the rails were really parallel.
Base with bed rails

The next step was to make up the gantry. Before starting I took a closer look at the monitor mechanism and realised that if I cut the excess off it, then I would get better clearance without having to make up a long bracket for the extruder. I timmed it off level with the ends of the rails (see the later pictures for clarity).

I then eyed out the second piece of chipboard and figured out that it could be cut into 4 pieces to make the front, back and sides of the gantry. As the two pieces of chipboard were square and indentically sized, this means that the 2 pices cut for the front and back match the width of the base. Fitting the sides to the outsides will square things up nicely.

When cutting the front section, I measured the cutdown Z-axis and used this as the size. The length of the sides was determined by the slot which existed in the piece of chipboard and what was left made up the rear section. I then finished off the gantry frame by screwing and gluing the 4 pieces together.

This is best illustrated by some pictures:
Y & Z gantry piecesY & Z mock-up 1Y & Z mock-up 1Base and gantry mock-up

The X & Z axes are just mocked up the picture as is the location of the gantry.

I decided to call it a day at this point as the next step involves two intricate bits of work:
  1. Fitting the X & Z-axes.
    1. These need to be both parallel as a set (easy on the Z-axis as it is a unit), as well as perpendicular to the other axes
    2. I am thinking about how to achieve this accurately, no decisions yet
  2. Figuring out and fitting the drive mechanism.
    1. The WolfStrap uses threaded rod (aka studding, aka allthread).
    2. The alternative is belt drive, but this requires pulleys. I do have some out of some scrap printers which may work.
If you have any comments or suggestions then please let me know by adding a comment below.

Sunday, 20 June 2010

Camper Part 29: Delightful Doors

You may recall that while I provided a detailed blog on the creation of the kitchen unit carcasses, I kind of skipped over the details relating to the worktops and getting the cooker and fridge in place as I was preparing for the MOT.

At that point, while I had created the carcasses, fitted sides, counter tops and the cooker and fridge. I had not yet actually panelled the front or fitted doors, drawers, etc.

The plan was to fit a complete sheet of 3mm plywood over the front of the carcass and then cut out the holes. This means that there will be few or no join lines on the front surface of the units. It also means that I could use the pieces cut out of the holes as the infill panels on the doors.

Earlier this year (just as the snow stopped) I started on the camper again and this was the job I tackled. Once I had the holes cut out (I can't get pictures right now as the camper is acting as storage for it's constituent bits), I was able to measure up the door sizes.

The doors are made of 32mm x 16mm pine batten (similar to what was used for the carcasses). The battens are formed into a rectangle with the left over plywood as an infill panel (kind of like a picture frame). This allows the door to overlap the carcass by around 10mm all round.

I decided I didn't want to get to fancy on the detailing as this is a budget camper, so the approach I took was as follows:
  1. Using my home table saw (I made a table to fit by handheld circular saw to), I cut a 3mm rebate into the batten for recessing the 3mm ply into later.
  2. I cut all the pieces to length with a 45 degree angle on each end for joining up. I tried to do this with a hand saw and normal mitre box, but its difficult to be accurate so I bought a cheap motorised mitre box (i.e. basic chop saw) on Ebay. It's amazing how much easier things are with the right tools.
  3. I had bought a band clamp from B&Q, so over the period of a week I clamped up all 6 frames (each had to stay in the clamp for at least 12 hours).
  4. The next step was to cut the plywood accurately to size. I did this by finding the center and measuring out from there so that the visible grain will match the carcasses. I did the cutting on my new (to me) band saw (Ebay again, it came with 3 spare blades and half the new price). Again proving the benefits of the right tools as there was no splitting of the ply as when cut by hand.
  5. The frames where then sanded to level out any gluing imperfections and then using a round over router bit in my new (to me) (Ebay) router table I rounded over the inside and outside edges.
  6. The final step was to glue and pin the ply insets into the frames. When they are dry Lorraine will help by doing the varnishing (she's the painter in the family). The carcasses will be done at the same time as they have already been sanded and are waiting for this point in time.
If the above is unclear then hopefully the following pictures will help make it clear.

Drawer frontDrawer front & cupboard doorDrawer front and cupboard door framesCupboard door frameDrawer frontsCupboard doors

Hinges and handles will only go on when they are fitted. The 3 smaller ones fit horizontally while the other 3 are vertical (i.e. the grain is always vertical). The narrower of the two smaller ones go under the sink. One will be a drawer front (under the draining board), while the other will be a false front, but I will make it open to give access to a shallow space above the fridge which will allow for storage of paperwork, etc.

Saturday, 19 June 2010

Workshop Worktop

As mentioned in the last post, our landlord was kind enough to agree to a bit of a clearout.

They removed various items and identified other for disposal. Of the items unsuitable for donation to charity shops, I made a judgement call on re-usable items and offered them on our local Freecycle group. Freecycle is marvellous for disposal and acquisition of goods which would otherwise end up in landfill.

I put a couple of mattresses online and got a response from a guy who is collecting them for his caving club. While chatting to him to arrange collection I mentioned using the old bed base to make storage in the garage and he asked if I wanted a 3m long length of kitchen worktop.

Not being one to look a gift horse in the mouth I naturally said yes. The bonus was that he offered to bring it over when collecting the mattresses. 40 minutes later I was the proud owner of a 3m length of brand new worktop. Turns out a fork lift driver had damaged 6 of them slightly (nick in the front edge), so the joinery company scrapped them.

As is usual there are always these little projects that get in the way as I then had to spend Thursday evening and Saturday morning upgrading my workbench to a 3.8m kitchen worktop based bench (I joined on a piece that I had left over from the camper's kitchen).

I'm back!!

I haven't blogged for a while as work, winter, family and other crisis have intervened to conspire against me.

But enough of the excuses, what have I been up to in the intervening time??

  • Lorraine's Lair has been completed (more pictures soon) and she has moved in. She uses it for arts and crafts as well as doing her Scout's admin (she runs Kyle's Cub Scout Pack).
  • I have made very LITTLE progress on the ambulance. I started on the frame for the water system, but winter intervened and I didn't feel like lying on my back on the drive so the whole project got parked. Earlier this year I managed to progress with finalising the kitchen cupboards (more in the next post).
  • I acquired an Armdroid robot arm (always wanted something like this since using one while doing my engineering degree). I spent some time trying to get it going without much success. Keep an eye out as it will be resurrected (probably with new electronics). Not soon though.
  • The robot arm reminded me of my intention to build a CNC lathe and also an interest in the RepRap project. I have now collected most of the bits to build a Mendel. The only bits I need are the plastic bits, but as they are very expensive I will be creating a RepStrap with wood (I'll blog more on the details later).
  • The above projects were taking place on the dining room table. Lorraine decided that the remaining half of the shed should become Craig's Corner instead of storage. This was my birthday gift, but as I am the only one in the household capable of doing the work I ended up making my own present. (Pictures will follow in a later article along with the Lorraine's Lair update.)
  • I've also helped my brother setup a blog as he is building a boat. Read about it here!
  • Finally (well, out of the highlights), our landlord came a removed a number of bits from the house and garage so this has given me some more space.