Machining

General Composites Discussions Composites Talk
#1

I have a question. I’m trying to figure out if it’s worth getting some parts machined. They are kind of a hassle for me to hand trim and besides for getting dusty and it taking time I’m thinking it would save me the headache.

My questions I guess are what is involved to get a machine to trim correctly?

What type of machine when I’m calling around? I saw I think 5 axis machines will work.

And what type of pricing am I looking at for a part that’s around 1/4th thick, 3 inches wide and 12 inches long with a few recessions and the side to be slightly beveled?

#2

I’m not an expert on machining but we do have a 5 axis router at work that we use to trim parts. We don’t do outside work so I can’t help you with pricing. I can say that once set up, the process is repeatable, quick, and accurate.

Do you have a CAD model of the part? You’ll need that. We use SolidWorks to model the part and then Surfcam to create the machine program.

#3

Ah ok. I figured that much.

I know someone that could draw the part in solid works I think.

Is it possible for a 3d scanner though?

And when you mention once the machine is set up I’m curious to know do you need to mount/secure the part the same way every time or roughly the same? Or does the machine have check points and then start from a common place?

#4

i’ve got some machining background so i can give you some insight.

i doubt 5 axis would be required to trim. and you’d probably hope that it wasnt. not to many shops have 5 axis machines, and people skilled enough to program that many axis, so that will limit your search and drive price to be less competitive.

what are you wanting to get 3d scanned? you mean scan your existing made part vs doing all the measuring and modeling in solidworks from scratch?
i’ll say this on that as well. theres only 1 real software company doing scan straight into solidworks, the rest usually capture point clouds. this will leave you with good reference points, but a LOT of work to still port over to a parametric model.
also, expect to pay 100-150$ an hr for scanning. and a small part will need several hrs.

not many places are going to want to machine CF in their machine as well, as it will make a HUGE mess, and i think the only real way to get good results in CF is using diamond coated tools, which they wont have on hand and are $$$, think 100$+ for a small end mill.

one thing most people dont consider is how much time is in the programming and setup, even before you hit run cycle. thats were most of your cost is usually. I used to set a machine up for an hr+, and the part runtime was 2min.
this is where they are going to hammer you on cost. you say i need 10 of these things done. you might as well go ahead and make 1000 because the price wont be very far off after you get the bill.

#5

Ah ok thank you for the information!

But yes you are correct. I was thinking that yes with a 3d scanner one could scan the original oem part then trim.

I don’t mind paying a little for a blade, and like I said I know someone that would just do me a favor and draw up the part in solid works no charge.

What machine would you say works best though so I could make a few phone calls?

#6

ive made some molds for propellers and done a jig that the part sits in ready to be trimmed, 2 at a time

it works very well , but its quite a bit of work to set it all up … the part holder (jig) has to be set straight in the machine (clocked up) , you need to make sure the part is held down in the same place every time. you will more than likely be doing a contour cut so clamping the part can be awkward as you cant simply clamp the sides of the part

if you not going to be making hundreds of parts , then i really dont think its worth it … specially not on a 5 axis machine

are you sure you need 5 axis ? cause if you can do it with a 3 axis machine then a normal cnc router will work fine and your cost will be considerably lower

do you have a pic of the part ?

#7

i dont think anyone is going to give you a quote without a print/file on hand. to much room there for them to be off and take a bath on the quote.

do you mind showing a picture of what youre trying to replicate?

i noticed you said blade and the next guy said propeller? is that right? so youre thinking about doing a infusion of a sheet bascially, then doing all the profile and 3d work on a cnc? man that sounds like a nightmare if thats the case.
if you want it CF. what about getting a 2pc mold made, and doing fiber reinforced plastic, or compression molding, like this.

http://clearcarbon.com/2013/wp-content/uploads/2013/05/Pre-preg-compression-molding.jpg

#8

Oh I saw blade as in cutting blade I don’t mind paying for if the machine shop doesn’t have that specific cutting tool.

My open mold is made but it’s not an issue if I had to make a top for a LRTM. But rather not since I have no experience. Although I could make these annoying little tabs that stick down the backside about 3/4ths an inch. Although they have a draft angle and that’s another problem…

I guess I’d rather not share a picture of the part as of right now since it’s not released yet but really just wondering is my time worth and potential error worth trimming these by hand.

The answer I’m coming up with so far is yes…