# How Do You Cut G10?

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#### TigerHawk

##### Reliving the good ole days
Just Google G10 material and you’ll get a few thousand choices.

You might try the rocket vendors first.
This vendor comes to mind,

#### hobie1dog

This vendor comes to mind,
those are very thin G10 sheets, as I was looking for .125 or 1/8" , as used on high power rockets.

#### hobie1dog

This still looks like the best all around thing to cut G10 with, and even though the Wet Tile saws are a little bit cheaper at $54... but these Rockwell BladeRunner saws are sold on eBay through the Rockwell site for$79 shipped and will do a lot more than a tile saw will. There's a Diamond tipped carbide jigsaw blade, made just like the ones used on the Wet Tile saws. AND no water to mess with, and a vacuum port to suck away dust. A mask and safety glasses would have you protected.

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#### hobie1dog

Mcmaster Carr has the yellow and green 1/8" sheet, and looking at Tensile strength it is higher for the Yellow. Pricing on a 4 inch wide sheet is hugely different.
Only 15 degrees difference in temperature ratings. ONCE PAINTED the Yellow would not have a Outdoor use issue with UV

A 4ft. long piece of Yellow is $27.50 A 4 ft. long piece of Green is$ 105.12

A good all-around choice, these Garolite G-10/FR4 sheets and bars are strong, machinable, and electrically insulating. They're made of a flame-retardant epoxy resin with fiberglass fabric reinforcement. Garolite G-10/FR4 is also called epoxy-grade industrial laminate and phenolic.
If you don't see the size you're looking for, please specify a length under additional bar lengths.
For technical drawings and 3-D models, click on a part number.
Bars
• Color: See Table
• Max.Temperature:
Green Sheets: 280° F
Yellow Sheets: 265° F
• Tensile Strength:
Green Sheets: 32,000-40,000 psi (Excellent)
Yellow Sheets: 35,000 - 50,000 psi (Excellent)
• Impact Strength:
Green Sheets: 5.5-9.5ft.-lbs./in. (Excellent)
Yellow Sheets: 5.5-12 ft.-lbs./in. (Excellent)
• Hardness:
Green Sheets: Rockwell M115 (Extra Hard)
Yellow Sheets: Rockwell M100 (Extra Hard)
• For Use Outdoors:
Green Sheets: Yes
Yellow Sheets: No
• Specifications Met: MIL-I-24768/27, UL 94 V-0
Yellow bars vary in shade from yellow-brown to light green.
1/8" Thick. (-0.012" to 0.012")
Yellow
Wd. 2 ft. Lg.4 ft. Lg.
4"8557K16$14.30$27.50

• Color: Green
• Max. Temperature: 280° F
• Tensile Strength: 32,000-40,000 psi (Excellent)
• Impact Strength: 5.5-9.5ft.-lbs./in. (Excellent)
• Hardness: Rockwell M115 (Extra Hard)
• For Use Outdoors: Yes
• Specifications Met: MIL-I-24768/27, UL 94 V-0
To Order: Please specify length in increments of 0.125" within the range listed.
1/8" Thick. (-0.012" to 0.012")
Green
Wd.Choose
a Length
Per
Inch

#### hobie1dog

Nice video review of the Rockwell Bladerunner:

#### mtnmanak

##### TRA & NAR L3
TRF Supporter
I have been getting all my fiberglass sheets from ePlastics for years. They sell the FR4 version of G10 (which just means it is fire resistant):

You can dial in any size and thickness of sheets you want from them and shipping isn't too bad if you buy in bulk.

I use a table saw to cut the sheets down to size for my Shapeoko 3 and then CNC out any parts I need. On big rockets (8" diameter and above), the fins can get too large for my CNC. If that happens, I cut the longer edges with my table saw, the shorter edges with my miter saw, then use a jig saw for any inside corners.

I use a standard plywood blade on my table saw and make the cuts with the saws outdoors.

I have CNC'ed up to 1/4" FR4 with no issues.

If you do go down the CNC path, pick up good endmills for fiberglass. I use some from Amana that are superb.

I realize a CNC router is intimidating due to price, size and a learning curve, but this Shapeoko has been awesome with a somewhat modest price point, not a huge footprint, and amazing functionality. I can't imagine going back to not having a CNC. I don't have a 3D Printer yet, but I am sure it is the same feeling people who do 3D printing have - hard to live with out once you have one.

Additionally, I firmly believe the CNC is WAY safer for cutting fiberglass in terms of airborne particulate matter. Using a vacuum system and relatively shallow cuts, you can't eliminate FG dust in the air, but it is quite minimal. You must still use PPE and operate in a ventilated area (I have mine in my garage and use a filtered vacuum with the exhaust hose routed outside), but compared to cutting FG on a saw, a CNC is practically dust free. If you plan to cut a lot of FG, I think the investment in a CNC more than pays for itself in the health safety alone, not to mention that you can also cut wood, plastic, metal, etc.

#### RCBrust

##### Well-Known Member
If you do go down the CNC path, pick up good endmills for fiberglass. I use some from Amana that are superb.
I CNC a lot of plywood but have yet to try G10/FR4. I looked at the Amana website and they have quite a few different styles of composite bits. Which type do you like?

Thanks,
Randy

#### mtnmanak

##### TRA & NAR L3
TRF Supporter
In 1/8" size, I like the Amana 48050-B or 48052-E

In 1/4" I like the 48011 and the 48052-E

I generally don't need to use sizes other than that. If I need to go down to 1/16", I usually use a good, coated single flute endmill and have no issues since I usually only need those small bits to make small holes, not contour cuts.

#### mtnmanak

##### TRA & NAR L3
TRF Supporter
Speed up the feed and reduce the depth of cut to give yourself a good chip load, but not bury the endmill (I am assuming you are using a home CNC like the Shapeoko, not an industrial machine. If you are using an industrial machine, go for it!). Cutting aluminum is way easier than FG. This FR4 is tough stuff. It has tendency to want to grab your endmill and send it burrowing down into your material in a crazy direction.

In some applications, FR4 can be stronger than aluminum. Consider a forward centering ring on a 100lbs rocket. That centering ring will most like have two U-bolt attachment points and have to handle the weight and shock of a 40lbs booster coming to a rapid stop when the main parachute deploys.

1/4" FR4 has almost the same tensile strength as 1/4" 6061 Aluminum (40,000 PSI for the FR4 and 42,000 PSI for the Aluminum), but the flexural strength of the FR4 is much higher than the Aluminum (60,000 PSI for the FR4 and 35,000 PSI for the Aluminum). So, in this application, both materials will most likely not break in any amount of force this rocket can produce, but the Aluminum has almost twice the chance of deforming under a high impact load (especially if it is hot). If the CR deforms, it is far more likely to fail (i.e. separate from the body tube and MMT). Further, the FR4 bonds to epoxy both mechanically and chemically (if prepped correctly), whereas the aluminum bonds very poorly to epoxy. For a plate that is likely to take a strong crosswise impact force, 1/4" FR4 often beats out 1/4" Aluminum.

#### RCBrust

##### Well-Known Member
Thanks for the info on the bits. My CNC is a ShopBot desktop.

Randy

#### mtnmanak

##### TRA & NAR L3
TRF Supporter
Thanks for the info on the bits. My CNC is a ShopBot desktop.

Randy
Ahh, totally jealous (in a good way) - the ShopBot is an amazing machine! Out my price range, though. The ShopBot will handle FR4 like a hot knife through butter.

#### RCBrust

##### Well-Known Member
How do the carbide bits seem to hold up cutting fiberglass? Hopefully I don't have to buy them in bulk.

Randy

#### mtnmanak

##### TRA & NAR L3
TRF Supporter
How do the carbide bits seem to hold up cutting fiberglass? Hopefully I don't have to buy them in bulk.

Randy
The coated ones hold up quite well. I have been using the same couple of 1/4" endmills for probably 6 months now with quite a few jobs on them.

As with most smaller endmills and hard materials, I tend to snap the 1/8" endmills off before they wear out. Usually that is because of an error on my part (DOC too deep, too fast, etc.). Doesn't happen often, but I think in the same 6 month period, I have broken maybe two of the 1/8" bits.

If you are used to cutting aluminum, many of the same principals apply. Ramping the plunge, adaptive cutting, etc will net you better results. Wood is super forgiving and you can usually just plough away and clean up with a downward cutting bit, but if you treat FR4 like you would treat Aluminum, you should be pretty close. After that, a bit of trial and error on some scrap pieces will dial in your optimal speeds and feeds.

#### Grog6

##### Well-Known Member
Any process that ends with breaking the remaining material off will end in an edge that is rough fiberglass, and will make a great glue bonding edge. waterjets are good, but you need to bake the residual water out of the material, it will make gorilla glue foam just where you don't want it to.

#### Zbench

##### Well-Known Member
TRF Supporter
How do the carbide bits seem to hold up cutting fiberglass? Hopefully I don't have to buy them in bulk.

Randy
Coated for anything other than steel is a waste of money. I too have a Shopbot desktop and I spin Onsrud bits with it. If you go to their website and download their pdf catalog, there is a section which gives recommended bits by material and Chip load for each.

They have a composites table and G10 is listed. I personally like the 52 series bits and I like to spin at 12,000 rpm. Assuming you have a high speed spindle and not a fixed speed router, 1/4” bit should take a .005” chip.

Using Shopbot’s Chip load calculator which is part of the control system, that would give you a feed speed of 2” per second. If you go through this every time which only takes a minute and update your tool paths with the proper feed, your bits will last indefinitely. If your bits are burning or leaving a rough edge, your rpm/feed ratio is out of whack. If your machine has a single speed router, you’d change the rpm to the output speed and resolve for the feed. Assuming 28,000 rpm, that would give you a feed of 4.6 inches/second.

Hope this helps. Buying expensive bits isn’t necessary if you understand the relationship between feed and speed.

#### RCBrust

##### Well-Known Member
Do you guys have any comments regarding the standard fluted composite bits vs. the burred style composite bits?

Randy

#### Zbench

##### Well-Known Member
TRF Supporter
Simple two flute upcut is all you need. G10 is not
Stainless. It’s really pretty soft compared to steel and especially carbide.

#### KC3KNM

##### Probably Wrong
TRF Supporter
Do you guys have any comments regarding the standard fluted composite bits vs. the burred style composite bits?

Randy
If I’m doing anything with flat composites at work, I’m typically using this type of cutter. They’re cheap, last long enough and leave a good finish in CF and G10. I cut all my composites in a small tank underwater to avoid getting dust and junk in the machine, which I’m assuming helps with the finish and tool life some so YMMV if cutting dry.

#### Sandy H.

If I’m doing anything with flat composites at work, I’m typically using this type of cutter. They’re cheap, last long enough and leave a good finish in CF and G10. I cut all my composites in a small tank underwater to avoid getting dust and junk in the machine, which I’m assuming helps with the finish and tool life some so YMMV if cutting dry.
Do you just mount a 'baking pan' to the table and mount the flat stock to the 'baking pan' (maybe with a plastic spoil board glued to the bottom of the pan)? Obviously if it is a professional machine, it is probably all purpose designed, but it would be interesting to know if that is basically what you're saying, as that's very accessible to home shops and would cut down on the need for crazy enclosures, vacuum dust collection etc., if you're only playing with composites and not wood.

Sandy.

#### KC3KNM

##### Probably Wrong
TRF Supporter
Do you just mount a 'baking pan' to the table and mount the flat stock to the 'baking pan' (maybe with a plastic spoil board glued to the bottom of the pan)? Obviously if it is a professional machine, it is probably all purpose designed, but it would be interesting to know if that is basically what you're saying, as that's very accessible to home shops and would cut down on the need for crazy enclosures, vacuum dust collection etc., if you're only playing with composites and not wood.

Sandy.

One of the first iterations was just a cut down plastic bin with a piece of aluminum bolted to the table through it. A bit of RTV sealed it and I’d face the work area before attaching the CF using masking tape and super glue. (Masking tape on both the fixture and part burnished down. Super glue tape to tape then fill with water. Part pops off and tape peels off, super clean and easy.)

The larger setup was just an aluminum plate, some aluminum channel, polycarbonate and a lot of RTV. As long as the base is something waterproof that can be machined flat I think you’d be set.

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