How deep is shallow and how deep is deep for a concave? Concaves follow the center line and rails right? they arent straight on both center and outline? and would it be bad to go from 1 concave to 2 then to a flat back end? Ive got most the board 3d modelled (Running it through my cnc machine then fine tuning the design by hand). The rails are radiused at 1/8" from the back then from 1' foot to 2' foot it transitions smoothly from 1/8" to 1/2" Then up from 2 feet from the nose it starts to transition from 1/2" to 1/8" My rails are basically 50/50. The board is 6'x18"x1-7/8." Im going to be surfing florida waves so i dont have much rocker on the board i want something i can use in the average crappy surf... It will be a 5 fin so i can switch between thruster and quad set ups...
I would say at this time 1/8" is shallow and 1/4" is considered deep (at the deepest point usually right in front of the side fins) . I would suggest you look at a bunch of concave bottoms with a straight edge.Regarding rails get a right angle square tool (?) and measure the rails of a board you like every 6" . Look at the bottom and side relief to see the flow and measure. “copy the best - you can’t go wrong - beats reinventing the wheel” - anonymous
How much do you weigh? I’m 205 pounds and I go with up to 3/8" under my front foot if I want a lot of lift, and the board is for clean water conditions - no wind chop.
If the water is bumpy, deep concave becomes almost unrideable. If smooth and glassy, it makes the board take off.
Maybe the 50/50 rails aren’t the best for your board. A harder edge on the bottom lets the board “slash” a turn more. 50/50 will tend to draw out a turn into a longer arc.
Sorry i come from a drafting background so all of my thinking is in radiuses umm hard edge how much of a radius would that be? and we seldomly have clean waves i mean not choppy but not clean... and im 145 pounds and 5'10"
I know alot about composites but when i get to imagining all the stuff together on a board the concave and the rails get me... I understand the crown on the deck and all that just dont really understand whats average and whats best for bottom stuff...
My favorite is concave starting about a foot from the nose, max under front foot, to dead flat in front of fins. From there, add vee. about 1/8" by the time it reaches the tail. Hard edges from front of the fins or maybe 2 feet from the tail. Hard edges at the nose. Mid body the bottom of the rail has about 3/8 to 1/2 inch radius.
In the middle of the board, the wide point on the rail is 3/4 to 1 inch up from the bottom, depending on board thickness. Your standard 60/40 rail.
high performance shortboards are all about concaves my friend.Spend the next few months going through the archives and you will learn so much it will make your head spin.
Those dimensions seem way too fine for someone of your size in very average conditions. You need enough foam to carry you through turns just as much as you need the foam for paddling.
I would add at least 1/2 to 3/4" to the width and bring the thickness up to at least 2 1/8. Remember you are surfing Florida not Bingin.
I doubt there is a pro on tour of your size riding a board that small.
I ride a 6' board right now 18-3/8" center nose 11" and tail 14.5 and its 2 inches thick single concave all the way and its super fast but not everything i want... I want a little more response... O and ill be making it out of aerospace composites, s-glass, and epoxy... lighter and stronger and floating more... so i would really feel like going smaller but yeah... And i wont have tons of crown on the deck giving me a little extra foam...
Single into double into flat can work - just depends on your transitions. You want to let the water out, not create a stop for water flow. So the doubles need to be inside the single and the flat needs to be where tail kick is lifting the bottom out of the way.
1.5" thick rails at 1" in from rail at centre of board. Assymmetric curve (think spiral, not circle). Smooth flowing curve from top deck tightening into bottom (still roughly 50/50). Undertuck bottom 7/16" to meet bottom deck at 120-140 dgree angle. Harden rearwards (less undertuck), soften forwards (meet bottom deck at increasing angle).
With these (less forgiving) rails you might add a touch of rocker, but the board will still be faster in all respects.
…BUT I’m just an inexperienced scraper, so any experienced shaper is invited to jump in here and criticise.
What kind of machine did you buy?
Well first of all my background will tell you about my machine... Well been building house with my dad since middle school... Been building skimboards and doing random composites and one off deals.. And now for a full time job building race cars (not the boss but im the only other person working with the company) and basically im building one based after the mechmate... The mechmate wasnt exactly what i wanted so i made modifications... i raised the gantry to get atleast 18 inches of clearance and my cutting depth will also be 18 inches... i was going to do ball screws but at the length of the machine (10'x4'x18") they werent worth it. Yeah everyone is going to say DIY cnc not very accurate... but there is so many things that go into it backlash, accuracy, tolerance, persision (cant spell). Yeah they arent as good as professional versions but they are way better then people are lead to believe... So basically a modified mechmate.
Yeah they arent as good as professional versions but they are way better then people are lead to believe... So basically a modified mechmate.
I know guys that have made homemade CNC with success. I guy I met from HOUSTON made some CNC machines to mill large parts for oil drilling. He didn't even finish High School.
Post some pictures. The key to doing surfboards is the fixturing on a cnc machine. To build one is not that difficult as long as your travel is true. The software is the brains anyway. The cutter head is also important.
Shape 3D works really well with CNC. I have been using it for 4 years. The lastest version is providing really clean cuts. In fact many machines around the world have converted to it.
If you need help with any file please feel free to email me and I can clean it up for you.
PM me for my email.
SD
I’m interested in your machine build. Keep me updated. I’m looking to build a Joes Woodworking machine but could easily be swayed…
You can cut EPS from a rectangular block on a flat bed and save yourself a lot of heartache in aligning blanks. Make sure you retain tabs so when you flip the board you can still use the flats to align with the bed. You can also try flipping the Y and X axis to optimise the cut.
yeah im going to have a manual axis from nose to tail so when the top is done you simply release the locks and rotate the board 180 so i can then cut the bottom with out re aligning... eventually that will be a true fourth axis but not yet.... and joes is good but if you are building anything with a far travel like mine 4'x8' you need to consider going with gear rack because of the long distance you need more holding torque with ball screws (bigger motors) and at long distance they get wobbly so thicker longer ball screws means lots of money... check out the mechmate (mechmate.com) you can modify but it helped me alot because everything is very specific. when looking at tons of forums combined we tend to get lost... dont get me wrong im always on as many forums as possible but yea i think you get the point...
p.m. if you have anyquestions im done with the control box build everything myself except the motor drivers and breakout board.. and im about 50% done with the mechanical stuff
Thanks for the info. I had a look at the mechmate and it looks good. I’d have to refine my welding skills (it’s been 30 years since I did any).
Yes, the drive screws become an issue on a long bed. Chain drives are possible, but I think lash is an issue. I have been considering a short bed and doing a board in 4 stages - front/back/top/bottom (Even half blanks glued together are possible with TFlex builds because the strength is in the skins, not the core). A lot of traditional surfboard manufacture CNC problems disappear if you don’t work with pre-rockered blanks and are not trying to retain the skin of blown PU blanks.
I’m interested in your solution to foam dust extraction .
there are alot of ways for dust most common are vaccuum systems under the table (bed) with holes periodically drilled and and tubes hooked up under the whole to the vaccuum motors, second really common is a ring around the router base with a vaccuum hose hooked up to it... Also you can hang plastic around the sides of the machine stops some dust but better some then none lol... Chains have tons of backlash. the gear rack for my system pinion, gear, pulley reductions is about 300 dollars... so not much at all... [im on a really low budget, (college student)]. Also it would be total hell doing the board in sections i thought about that but said why the hell not lets just go all the way... I got most my metal from a old trailer then bought about 200 dollars worth. the most money spent was the electronics... Motors, drivers, power supply. Also you prolly know that most machines are designed for long z axis's you will have to take that in mind when designing... Add clears and strength to the z axis so it doesnt flex at that distance... if you wanna save more money you can build the table oout of would then track up all metal
and you shouldnt have to worrk about gluing haves together alot of people say you cant glue a board back together but thats bull crap done it many times... (i only use epoxy and s-glass even for repairs, i havent build a board from scratch yet though, hints the concave and rail questions) But when i make skimboards the foam for that only comes in certain sizes where i always have to clue it together.. but the epoxy is stronger, lighter, and flexs more then the foam so no trouble there. Surfboard foam is crap though so not really the best idea.