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Loading ...Measuring and cutting
syrillian
“Thank you” to the individual that sorted out the image issue. Please bear with me as I am an old dog trying to learn new tricks.
Safety is once again paramount. I forgot to mention in my last post that loose clothing, dangly jewelry, and long hair can be quite dangerous. Dressing and coifing appropriately will see you through the day with all your digits, limbs and scalp still in place.
There are basically three types of cuts that apply to this build; rotary tool, circle saw, and router bit. These are listed in the general order of cleanliness of the cut from roughest to smoothest. This may vary depending upon the condition of the tools and the cutting implements, but all things being equal, a rotary tool cut is the roughest, and router bit cut is the smoothest.
Note that a table saw with a 10” (75-80 tooth) blade designed for cutting plastics will yield a cut comparable or exceeding the quality of a flush-rout cut. Also bear in mind that these blades can be rather costly; the last one I priced was about US$ 100.00
Before I move on it is notable to mention that there are two basic types of acrylic; “cast”, and “extruded”. Cast acrylic will not suffer the “melting” syndrome that extruded acrylic seems to suffer from when exposed to the gentle ministrations of a power tool that cuts.
Here is an image depicting the cuts (from top to bottom: Dremel, Circle Saw, Router)
The rotary tool cut will require some sanding before it can be used for capillary bonding, and a considerable amount of sanding prior to polishing (capillary bonding and polishing will be covered later on in this Log). Both the saw cut and the Router cut are ready for bonding, and need far less sanding for polishing prep-work.
One subtlety that can ruin a project is how out of square the panels are. “Square”, as in how close to 90-degress all applicable angles are. This project will be constructed with all angles at 90-degrees. For the most part angles that are off-square by 1/32” across a 12+ inch edge can be fudged to work and look okay. One pitfall is that such errors and inconsistencies may cause minute gaps between two panels that need to be bonded together; the gap prevents a full and proper bond.
When I mark a place to be cut I use a “v” shaped mark with the convergence-point at the line to be cut. This allows for a more accurate visual marker than a single line. Using a dot also works well, but can be a strain on the eyes.
Cutting with the Circle Saw:
Measuring and accounting for built-in measuring gauges and guides on tools will save a lot of frustration, time and money (speaking of measuring, please be patient with me as I may switch between Metric and SAE throughout this Log).
I use a 2’ level as a straight-edge guide when I use the cordless saw. To ensure that a cut is right the first time, there are several things to consider: Blade width, Guide width (on the saw) and which side of the line on the acrylic that the saw blade will cut.
There are several methods to use, but I will describe the one that works best for me and keeps me from making too many mistakes.
The guide on the saw is 1” wide
The Blade is 1/16”, but with the angle of the teeth the effective width is 1/8”.
You may notice that in the next image of this acrylic panel that the line is not entirely bisecting the “v” mark. There are 2 basic methods for cutting along the line:”Leave the line”, and “Remove the line”. I choose the former as I can see that the cut is correct, wherein removing the line removes the marker. This allows a little leeway for sanding when necessary.
1” out from the guide, and 1/8” less to account for the blade (but you will want to make certain that the measuring tape is butted up against the rail… unlike me in the pic below.
Using an angle, level and tape measure to set up the guide:
Clamped down:
Ready to cut:
Always: Measure twice, cut once. When the guide or jig is clamped into place I always check all relevant measurements again prior to cutting.
As I cut the panels to size I mark them appropriately with what panel it is (front, back, top, bottom, etc., and the orientation (up, down, front, back, etc
A rotary tool can also be used to cut straight lines; it will require the sideways bit.
You will also need the straight cut guide attachment.
The simplest way to guide the cut is with the edge of the panel that is being cut.
This attachment should also have its own markings for measurements which makes it very handy to use.
The next installment will cover profiling and cutting holes in the acrylic.
My apologies for the inconsistent image sizing and quality. I am still trying to work out the error that seems to exist somewhere between the chair and the keboard.
I`m finding your log very interesting I have had an acrylic case imported from France but have modified it quite extensively.
I have struggled with bonding as the glue ive used is visible and as i`m working in clear UV reactive acrylic i want an invisible bond. i have read about capillary bonding as it leaves no trace so i will be interested to find out what you use. i`ve heard weld on is good but have been unable to track the correct stuff to the uk. I saw your beautiful build when it was featured and was blown away so i will be following this one closely
lol sorry i seam to have double posted. you can remove these i`m sure
Hi, urbtree.
Thank you for your interest and your comments.
Indeed, capillary bonding should yield results that make you smile. It takes a little practice, but once one has it down there will be nothing but the cleanest of seams.
Thank you for your kind words in regards to that behemoth, Gemini. I have since re-designed, scaled down and built another case that is very similar, Halcyon.
i`ll look forward to seeing it and wait with baited breath for the next instalment. the parts of my w/c have started to arrive so i`ll be on with the sticking soon.
Hi Daniel, I will follow this blog with interest. I have been a modelmaker and plastic fabricator for 25+ years and had to make my own tools and jigs in the early days too.
I have not seen mention of a cabinet scraper so far. Although used by woodworkers to give a fine finish, it is invaluable for deburring the cut edges to save your blood getting everywhere and removing saw marks.
It may also be worthwhile constructing a bed for the circular saw which would allow you to cut panels square and the same size, when necessary. Once set to be square, a simple stop would ensure true cuts every time. I will hold off now until you get closer to the ‘mounting of hardware’ section, since that’s the bit I am working on at present.
For all those readers who are wondering, the basic bonding agent for acrylic is dichloromethane, but cast and extruded acrylics require slightly different formulations and additives. ‘Extrufix’ is made by Evode in UK, and should be available from all plastic sheet stockholders. It works on cast too but since I tend to use Tensol 70, a two-part epoxy, for cast, I will check out a suitable alernative.
Buff polishing is preferred for work at home since it will not engender the internal stresses which are produced in flame polishing, which can adversely affect the appearance of clear acrylic by fine cracks appearing. If you can get hold of them hypodermics and needles make applying capillary cement an easier job, but a good quality soft paintbrush can hold a useable amount too.
Greetings, Bottle of Dog.
It is a real pleasure to meet you.
Thank you for your comments, they are an excellent enrichment to this build log. With your permission I may call upon your expertise to clarify or perhaps describe in better terms the techniques that I am using. My verbage in this trade is less than desireable as I am merely a hobbyist that has learned through trial and error….mostly error. Although I have built about a dozen full-cases from acrylic I find that there is always new ground to break and new things to learn.
I have indeed used a cabinet scraper for de-burring and used simple home-made jigs, saw guides and “boxes” to guide my (at times) not so steady hands.
I will be posting again in about a week. I encountered a set-back as I have returned to 6-day work weeks.
Again, thank you for your additions and insight.
Respectfully, Daniel
Hi Syrillian, me again 
Just wondering where you got your table saw from in the original post? Im trying to find one for around £50 as it will only be used for acrylic, but the only semi good ones are for tiles, do you know if this blade would work?
Cheers
Hi, mrtk.
If you mean the blade? Then, no.
If you mean the saw, then perhaps. The Dewalt that I have (purchased online via that auction place) spins at 3850 rpm, a typical tile saw (MK Diamond 101) spins at about 3450. I don’t think that the rpm variance would make much of a difference; it is the arbor size and configuration that might trip you up…. nothing a little mod can’t fix.
Hmmm… now you have my interest piqued. Tile saws have a sliding tray. Such a device might prove to be quite the blessing as it also means a solid mitering surface.
Nice…. thanks for that.
Funny. I work in the tile industry, and have walked past the saws in our warehouse numerous times and never thought twice about it.
Guess I’ll be looking at one tomorrow.
I should add that there is a
LARGE SAFETY ISSUE.
(sorry, not yelling. Merely stressing)
A large portion on the blade is out in the open (no shroud or protection), and front-and-center to boot.
That is dangerous.
…but I will still look.
I just got a tile saw syrillian, if your on the forums look out for my mod log, ill get a few pics up there of it once i get started.