Drilling through multimaterial complex holes

Author	Message
Jones	J Jones posted 6 Years Ago HOT Topic Details
J Group: Forum Members Posts: 18, Visits: 1.6K	I'm looking to join two matching 3d shaped carbon fiber sheets together with M4 screws and threaded inserts (the threaded insert can't stick out on either side) and I need a few hundred of those holes... The stack I will drill through is: one sheets is 1mm carbon and glass and the other is 1.5mm carbon, 5mm solid epoxy (core), 1.5mm glass. The shape is not flat so a drillpress is not an option. The space for a drill cup is also probably to small. But on the other hand perfect 90 degree holes are not necessarily needed. It might also be hard/inconvenient to strap a waste board on the backside to prevent chip-out/blowouts because of the shape So my question is how do I tackle this the best possible way? I guess making a jig to locate and clamp down the two pieces in place. Find a suitable M4 drillbit that lasts, ideally one that doesn't produce blow-outs and is self starting Drill through both sheets. Enlarge the hole in the thicker carbon piece and find a suitable threaded insert. Hum... Edited 6 Years Ago by Jones
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Steve Broad	Steve Broad posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Jones - 1/22/2019 9:56:06 AM I'm looking to join two matching 3d shaped carbon fiber sheets together with M4 screws and threaded inserts (the threaded insert can't stick out on either side) and I need a few hundred of those holes... The stack I will drill through is: one sheets is 1mm carbon and glass and the other is 1.5mm carbon, 5mm solid epoxy (core), 1.5mm glass. The shape is not flat so a drillpress is not an option. The space for a drill cup is also probably to small. But on the other hand perfect 90 degree holes are not necessarily needed. It might also be hard/inconvenient to strap a waste board on the backside to prevent chip-out/blowouts because of the shape So my question is how do I tackle this the best possible way? I guess making a jig to locate and clamp down the two pieces in place. Find a suitable M4 drillbit that lasts, ideally one that doesn't produce blow-outs and is self starting Drill through both sheets. Enlarge the hole in the thicker carbon piece and find a suitable threaded insert. Hum... Some photos would be very useful :-)
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Jones	J Jones posted 6 Years Ago HOT Post Details
J Group: Forum Members Posts: 18, Visits: 1.6K	sorry I don't have any real life samples or cad drawing of it yet but this is the best I can come up with atm.
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Steve Broad	Steve Broad posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 408, Visits: 4.1K	+x Jones - 1/23/2019 11:18:10 AM sorry I don't have any real life samples or cad drawing of it yet but this is the best I can come up with atm. Sketches are probably more informative than sterile CAD drawings :-) Initial thoughts Without knowing the overall size of parts I have to make assumptions. Make a support that fits snugly to the underside and clamp both to the drill bench. This will also help to prevent the glass fibre from splitting on breakthough. Clamping a curved strip of aluminium to the underside should do the same job re breakthrough. Do the parts have to be detachable? Take a look at this video re combining glass and carbon (opinions on this video from the experts on here would be informative). If no stresses involved then not an issue. https://www.youtube.com/watch?v=j7bQYEt_qtU
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Jones	J Jones posted 6 Years Ago HOT Post Details
J Group: Forum Members Posts: 18, Visits: 1.6K	+x Steve Broad - 1/23/2019 12:39:10 PM +x Jones - 1/23/2019 11:18:10 AM sorry I don't have any real life samples or cad drawing of it yet but this is the best I can come up with atm. Sketches are probably more informative than sterile CAD drawings :-) Initial thoughts Without knowing the overall size of parts I have to make assumptions. Make a support that fits snugly to the underside and clamp both to the drill bench. This will also help to prevent the glass fibre from splitting on breakthough. Clamping a curved strip of aluminium to the underside should do the same job re breakthrough. Do the parts have to be detachable? Take a look at this video re combining glass and carbon (opinions on this video from the experts on here would be informative). If no stresses involved then not an issue. https://www.youtube.com/watch?v=j7bQYEt_qtU O yeah iv'e gone through and tested the concept and it's not an issue but it's quite complicated so I wont go into further detail about that. iv'e actually seen that video before, he makes som good content. i assume I have to go and get myself som kind of backing to prevent the glass from splitting. Would a soft ish foam material do the trick? What would be the preferred drill bit for hand drilling and what kind of inserts would be best suited?
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scottracing	scottracing posted 6 Years Ago HOT Post Details
Group: Forum Members Posts: 460, Visits: 5.2K	ideally you need to be looking at PCD or carbide cutting tools for this, especially with the amount of holes you are producing. What inserts are you using? are they parallel bushes or top hats? and what are you using to bond them in?
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Jones	J Jones posted 6 Years Ago HOT Post Details
J Group: Forum Members Posts: 18, Visits: 1.6K	+x scottracing - 1/23/2019 1:24:36 PM ideally you need to be looking at PCD or carbide cutting tools for this, especially with the amount of holes you are producing. What inserts are you using? are they parallel bushes or top hats? and what are you using to bond them in? Are they robust enough to be used in a regular hand drill? The core is just 5mm solid epoxy and 3-4 600 gram plies top and bottom. Well it can't be sticking out either side and most M4 inserts are longer then the 8 mm plate, so I'm not sure what is best or how to get around it...
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