small parts

[inpro]

Is there anybody who can help us with this problem: when we attach a sheet of styrene on the top of our 3-axis router with double sided skotch tape, it is unpredictable when it will loose and by this spoil the finest details. We are trying to discover another way to attach the material on the maschine. If anybody have an idea please share it. Thanks in advance.By the way we are in scale modelling for architectural projects and we use finnest instruments,for example flat 0,6mm tools.

[turmite]

Hello inpro,

I know a young man in Bulgaria but I only speak and write English! First, what thickness is the sheet of styrene and how large are the parts? I don't know if vacuum would work or not. High volumn might, but it will be expensive. Are the parts 3d objects or more along the lines of flat work such as trim pieces?

Mike

Originally Posted by inpro Is there anybody who can help us with this problem: when we attach a sheet of styrene on the top of our 3-axis router with double sided skotch tape, it is unpredictable when it will loose and by this spoil the finest details. We are trying to discover another way to attach the material on the maschine. If anybody have an idea please share it. Thanks in advance.By the way we are in scale modelling for architectural projects and we use finnest instruments,for example flat 0,6mm tools.

[inpro]

Hi, turmite and thanks for your concern. For the finest details/for example railing of a balcony/ we use 0,5mm styrene /polystirol/ and stick it on the plot. Usual task will be bars with 0,3-0,5mm thickness. I am almost sure that vacuum will not work because of the size of the details. Some guys suggest us better double sided tape, but then we have problems with removing it and not demolishing the parts. Still trying.

[Torchhead]

I cut a lot of small PCB's and faceplates from sheet material. Nothing less than 1mm. One of the things I have learned is to use "tabs" when cutting the profiles of the objects. It holds the pieces in place and you can easily break out the part or cut the tabs by hand. Small pieces don't go flying off to hide in dark corners!

Check out SheetCAM software to layout the toolpaths (www.sheetcam.com) It has a tabs feature that is very handy.

[arie kabaalstra]

i know a guy in holland who makes scalemodel kits from sheet styrene, his secret?.. he once told me: just stick a sheet on to a nylon plate on the machine with a water solluble glue, run your program, and soak all in water.. glue dissolves, and HEY presto! PARTS! works for me.. gonna try it soon.. as soon as my machine is finished...

[Stepper Monkey]

We have slowly developed along the lines of the last two posts - we hold the stock with a simple hot glue gun by running a fillet of glue down the angle between the table and the edges of the stock only. This allows it to sit flat on the table and still very firmly resist movement.
We then cut with tabs, removing the finished items first, and leaving only a very thin frame of stock to be peeled up with the glue, which leaves no marks or residue on the metal table surface.
For fragile two-sided items like your railings we no longer "flip" the stock. We often just cut both left and right halves at once and solvent weld them together if standard fixturing or indexing would be problematic.

[under-dog]

Originally Posted by Torchhead I cut a lot of small PCB's and faceplates from sheet material. Nothing less than 1mm. One of the things I have learned is to use "tabs" when cutting the profiles of the objects. It holds the pieces in place and you can easily break out the part or cut the tabs by hand. Small pieces don't go flying off to hide in dark corners! Check out SheetCAM software to layout the toolpaths (www.sheetcam.com) It has a tabs feature that is very handy.

I agree with this method. let me elaborate. Styrene is cheap. Destroying a part is not. Make the sheet sufficiantly over sized and screw clamp or whatever the sheet down in the outer waste zone("frame") . Make tabs or connecting runners from the actual parts to the "frame" in areas that are easy to detach and clean later and also provide sufficiant and proper support for the piece being cut. You will generally end up with something similar to what you see in a model kit with a part that is suspended in a frame. This can be combined with the double sided tape so thier is no movement.

If the parts are just detail applied to an existing substrate and there is no change to the outer profile of the substrate then double sided tape and maybe trap the ends with some sort of indexing pins, blocks or something. better yet a material like sacraficial wood blocks so if you hit them it wont screw up your machine or stall your program. The tape will hold the piece down and the blocks will trap the edges against shear force created by the tool movement and stop the piece from sliding laterally.