Drilling Acrylic Panels

Drilling holes in acrylic sheet is easy with a small modification to the cutting edge of the drill. You should then have clean holes with no cracking in the acrylic.

Shown above is a small drill with the cutting edge suitably modified such that it has a “scraping” action, rather than digging into the plastic. The diagram below shows the effect required. Some sources indicate that the included angle of a drill for acrylics should be around 60° rather than the normal 120°
I don’t subscribe to this view as it is already difficult enough to grind the cutting edge of very small drills without having to alter the included angle as well. I use standard drills and just “blunt” the cutting edge as shown later.
Drill angles
Here is a set of modified drills I keep on the workbench with a piece of drilled acrylic so that I can test the fit of things like switches, bolts and screws etc.
This is one way to produce the “scraping” effect on the cutting edge. Use a Dremel tool mounted in a holder or in a vice with rubber jaws.
Make sure you wear eye protection and a face shield in this operation.
It is also possible to “touch” the cutting edge on a fine bench grinding wheel provided it has sharp corners but the Dremel is best for tiny drills. This photo shows a diamond impregnated disk but a normal brown abrasive disk will work (with a face shield). Do both cutting edges on the drill.
I always use a magnifier to carry out this operation.

Here is an interesting link from an Aussie Plastic Fabricator on how a pro sharpens his drills and other tools for plastic.

Strain Relief

Not actually how to fix a hernia! but more about how to ease the problem of working under a fixed layout.

With advancing age it becomes increasingly difficult to work under the layout. There are some alternatives such as tilting or fold-up layouts but they have disadvantages. I didn’t want a portable layout so my layout is screwed to the walls and supports. The layout height is 1020mm (3’4″) with a floor to head clearance of 840mm (2’9″) under the layout. Having the seat close to the floor was mandatory.

So I had to figure out a way to work with at least some comfort under the layout. I tried a very low stool on rollers but on my lino floor it was just too prone to sliding around (rocketing around might be a better explanation) and had no back support. The back support is what I need along with a stable base.

 

This is the prototype (and final product) to allow me to drag it around the floor. Made from workshop offcuts (pineboard and MDF) and some old fabric padding.
The other bit of padding on the floor looks like an offcut and it is – but I use it to kneel on while I roll (collapse) into the seat.
I just experimented with the back angle, hence the hinges plus they were also laying around the workshop. The other gadget visible in this photo is a locking clamp to which I have attached a roll of solder.
This is clamped up under the layout on some appropriate part of the frame and provides solder at a level close to the work.
When soldering under a layout DON’T have any part of your body UNDER THE SOLDERING AREA for obvious reasons.

Lifting Entry Flap/ Section

Easy Access without Crawling Under

A light weight lifting flap (entry panel) to make getting into and out of the Layout Room  easier than ducking under. Especially for an around-the-wall layout and useful for geriatrics!
The panel has an electrical interlock which cuts all power some distance
either side of the panel when it is raised a few millimetres. That still doesn’t cater for person who attempts an “underpass” but rises a little early, distributing locos etc. onto the floor.  I think a mechanical interlock is the next project!

This is a view of the completed lifting section before scenery. The hinges will be covered by a scenic “feature” (!)
The non opened clearance under is 950mm (3′ 1.5″) for tiny people and flexible adults. This has been in use for 4 years with no problems but normally opened to enter. My mechanical wire-in-tube manual point control is visible. Works well but I have been seduced by the magic of MERG (worth looking at even if you only download the EXCELLENT free “Electronics for Model Railways” book) and using electronics, DCC and computers is my thing, so all are in the process of conversion to servo control, the fitting of which is the subject of this post.
Preparation of the bench work either side is critical, as is assuring that the whole thing is level fore and aft.
This shows the basic construction using quality light timber (in this case hoop pine – Araucaria cunninghamii). The joints are all epoxied together and reinforced by using biscuit joiners.
The CRITICAL consideration is that timber shrinks and swells ACROSS THE GRAIN and there is very, very little shrinkage along the grain.
So as much longitudinal timber as possible must be used across the opening so that damp/dry weather changes have minimal effect. The next photos show other additions to further reinforce that in the other direction.
The underside showing additional cross bracing, both to support the 1″ (25mm) foam and to restrict any shrinkage or expansion at right angles to the track so that the latter remains aligned where it crosses the joins. There has been no problem with track alignment or binding of the lifting panel since July 2014 even through flooding rain periods and temperatures in the room between less than 10°C and over 32°C.
The section alongside the lift up section has been prepared to accept the 2″ foam. This photo shows a hinge rebated into the support.
The hinged side. Quality heavy duty brass hinges (3″ 75mm) were rebated into the frame and panel and the foam is being bonded to the top of the layout with PVA & weights (no, this is not a Valvoline advert!)
The “landing” side carefully fitted so the top surface aligns when shut.
A later photo showing the H/Duty micro switch interrupting the DCC feed to the section behind.  The inset shows the one on the under side.
Underneath with the wiring necessary for the track on the lifting panel.
The track feed to the lifting panel has two terminal blocks near the hinge line and a short section of flexible cable which can be replaced if necessary.

 

The joins across the lifting hatch require a little bit of care and attention.
Track is laid straight across the join substituting PCB sleepers at the join. Doing 5 sleepers would be better than 3 for more surface contact. The conductive copper is removed between the rails. I used a paper sanding disc in the Dremel before soldering them in place. Clean the copper and the bottom of the rail with a flux. “Tin” the surface of the copper PCB and you will need little if any additional solder to sweat the rail in place.
I always attach the track to the substrata with diluted Carpet Glue (latex adhesive). It is quite thin, very cheap, and only needs application to the foam / wood etc followed by weights to hold it in place until dry. The great advantage of this method is that there is no mechanical connection to the substrata AND … it can be lifted if you have a stuff-up. Just brush some water over the track or point (turnout) you want to lift, leave if for half an hour or so, then carefully slide a thin spatula under it.
After the latex adhesive has set, cut the track with a very fine blade. I had to cut a sleeper as the track was diagonal at this section.

Also see the section on “Laying Track Across the Join” Yet to be added.