Spade or Forstner for drilling Royalex
Posted by: melenas on Oct-14-13 9:50 PM (EST) Category: Canoes
I'd like to drill my RX canoe hull to install some painters. Some seem to recommend a Spade drill bit, including the instructions for the Tugeyes I got, others a Forstner bit.
I only have a wireless drill. Can a Spade bit shatter Royalex? I guess the Tugeyes would cover up any rough edges caused by the drill bit. Any advice much appreciated.
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- Spade or Forstner for drilling Royalex - melenas - Oct-14-13 9:50 PM
Posted by: carldelo on Oct-15-13 12:39 AM (EST)
-- Last Updated: Oct-15-13 12:41 AM EST --
If you can afford it, a Forstner bit is always better than a spade bit. If you happen to have both, it's a no-brainer, use the Forstner.
For plastic, a hole saw will also work well, and better than a spade bit. It depends on the diameter, of course, hole saws don't come less than 1-1/4", I think.
For diameters less than about 3/4", you can just use regular high-speed drill bits, be sure to use new, sharp bits and work your way up to the final diameter in 1/8" increments.
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high speed drill bits|
Posted by: pblanc on Oct-15-13 7:06 AM (EST)
I have used high speed drill bits many times, using progressively larger bits for larger holes. I have also used hole saws (as for cutting an exit for a through-hull fitting for a bilge pump) and spade bits and they have all worked.
A Forstner bit probably is superior, but not necessary base on my experience.
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high speed vs low speed drill bits?|
Posted by: melenas on Oct-15-13 8:51 AM (EST)
I assume by high speed drill bits you mean "normal", all-purpose drill bits, as opposed to either Forstner or Spade bits, which are low-speed?
The hole will be 5/8.
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Forstner if you have one|
Posted by: somalley on Oct-15-13 9:11 AM (EST)
I've drilled various sized holes in Royalex, from 3/8" for grab loops up through nearly 2" for a bilge pump outlet. Forstner bits work very nicely for bigger holes. For holes under 1/2", brad point bits let you drill the hole in one shot rather than having to progressively step up the hole size.
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Posted by: magooch on Oct-15-13 9:20 AM (EST)
I'm wondering if there isn't a better way to attach a rope to the boat than to drill a hole through the hull.
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One purpose of tug-eyes|
Posted by: Guideboatguy on Oct-15-13 11:00 AM (EST)
-- Last Updated: Oct-15-13 11:39 AM EST --
Sure you can just tie a rope to the carrying thwart, if there is one. That's usually what I do if there's not already a through-hull attachment point, and it's what I do for tie-downs on the car roof since that way there's no side-to-side movement possible between two opposing tie-downs like there is if those opposing tie-downs attach to a loop that goes through the hull (the bigger the loop, the farther the boat can move one way or the other before stopping). But attaching a rope much lower than gunwale height on the hull is better for such purposes as lining through rapids. The ideal lining attachment is a bridle which puts the point of pull directly under the hull, on the keel line, because then, no matter how sideways to the direction of pull the boat might turn when in strong current, it won't flip. Putting your attachment point a lot lower than gunwale height by means of a hole through the stem does a lot to reduce flip potential when the boat gets crosswise to the current, even if it doesn't completely eliminate it like a bridle does. All that is based on the idea that a tug-eye is even needed, which it would be if the attachment point were very low on the stem. As Pete points out below, for attaching a loop well above the waterline, simply drilling through the hull is all you need to do (no liner tube is needed).
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Brad point bits|
Posted by: carldelo on Oct-16-13 9:35 PM (EST)
That's a good point - brad point bits are very good for this. Probably better than Forstner, actually. A Forstner bit used in a hand drill can just about break your wrist if you're not careful and drift off of a perfectly straight hole. A brad point bit is more forgiving, i.e. easier to control during minor misalignment. If you're using a drill press, either is fine.
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Posted by: ezwater on Oct-15-13 2:26 PM (EST)
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On Royalex, just drilling through the |
Posted by: ezwater on Oct-15-13 5:41 PM (EST)
hull at the right height for lining is OK.
If you're dealing with a very light hull, a composite hull, I don't think the Tugeye route is safe, whether just drilling, or installing a threaded spacer.
What Kaz of Millbrook does is to attach a strap to the hull, without drilling. This requires some experience or common sense about how to fray the ends of a strap and then use epoxy (G-flex suggested) to attach the strap ends. Kaz sometimes puts the attachment just below the gunwale, not ideal for lining, but to take advantage of the gunwale stiffening the thin, flexible layup.
This method can also be used on Royalex. Use a sharp, low angle chisel to skim the vinyl off the ABS where the strap will be attached. Then G-flex the strap ends to the ABS. Maybe it could pull off, but if it does, that may be better. You don't want to destroy a hull in a desperate extraction attempt.
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staged pilot holes?|
Posted by: melenas on Oct-16-13 11:30 AM (EST)
When using a Spade/Forstner bit, do I drill several successively larger pilot holes using Spade/Forstner bits, or do I drill the pilots with a brad point?
Another way to phrase the question: are pilot holes always drilled with the same type of drill bit as the final hole?
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Posted by: pilotwingz on Oct-16-13 11:53 AM (EST)
..... when you use a spade , forstner or brad point you never drill a pilot hole , and never increase the bore size in succession .
Although it can be done (by those who are experts at fixing their mistakes) , it is a nasty , dangerous and improper method that can easily tear up the material you are boring through .
With those bits it's a one time bore at the correct size desired .
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Posted by: melenas on Oct-16-13 12:32 PM (EST)
for preventing a disaster! I would have drilled pilot holes for sure.
As a handy man, I am in the apprentice stage. When DO you use pilot holes, then?
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same as Carldelo has said ...|
Posted by: pilotwingz on Oct-17-13 12:23 AM (EST)
-- Last Updated: Oct-17-13 12:51 AM EST --
..... generally termed "Chisle point" or "Twist drill" bits are the type of bit most people (who haven't familiarity with the array of drill bits available) , would think of when they hear the words , drill bit .
It is common practice to drill a "pilot hole" with a smaller size Chisel point bit , and then graduate with a larger (and larger again if req.) size to achieve the desired finish bore size .
This process although common practice is not required , and in truth makes no difference what so ever in the satisfactory completeion of a bored hole ... but do it that way if it makes you more confident .
Chisel point bits are not all the same . They have varying tip angles , varying chisel angles , and differing rates of flute (twist) . Different materials being drilled by Chisel point bits (because of the materials properties) , are best drilled by the proper Chisel point bit designed for the specific material ... but that gets into a more specialized aspect of boring holes , and "generally" not so important to the everyday guy/gal with a drill in their hand .
I will offer you one tip regardless the bit you decide to use ... take a center punch (pointy object) and mark a respectable dent in the exact center of where you want your bit centered . Just "tap" the center punch with a hammer to make the mark .
For what you want to do , boring a 5/8" hole through a Royalex hull , no matter which bit you decide to use ... the results will all be resonably the same if you use a "backer block" held tight up against the inside .
Time to drill your hole now , and not worry too much , it's going to be OK even if it's not perfect , it will be fine . I would use the Forstner , but it's not a mandatory requirement , they all work well enough for your needs .
The most important thing about any bit ... is that it's fresh and sharp . Boring holes with dull bits is improper practice and can leave less than desired results ... or worse !!
ps., ... I want to renage a tad on what I've said to you . You "Can" use a tiny weenie pilot hole for your operation , such as a Chisel point 1/32nd size . This will not effect how a Forstner , Brad point , or larger Chisle point works ... what it will do is allow you to know exacly where to hold the "backer block" (chunk of 2x4 , etc.) so you don't drill into the hand holding the block by mistake !! ... You understand what I just said , right ?? ... This same tiny pilot could act as your center punch as well .
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Posted by: Steve_in_Idaho on Oct-18-13 11:54 PM (EST)
Definitely not the spade bit. They are notorious for producing out-of-round holes. The Forstner would be okay, as would standard twist bits - but brad points are best. They tend to not wander, and make nice clean holes. Hold a sacrificial block behind each hole as you drill through for best results.
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