Mitering and tacking the front triangle // Romax Build Part 1 – Framebuilding 101 with Paul Brodie

0 Comments 12:52 pm

hi i'm paul brodie this is my shop the 
man behind the camera is mitch and   i'd like to say welcome last week we did a 
frame drawing of a romax i'm going to make   myself a romax it's been a long time since i 
did that up on my bench here i have a couple   frame jigs and i want to i want to talk really 
uh briefly about them this one was made in 1985   and it's done a lot of frames it's done over over 
4 000 frames and it's still going i was teaching   frame building 101 and this was the only frame jig 
we had so i made another frame jig i made this one   in 2015 so it's it's three decades apart and they 
look a lot the same but you'll notice that my new   one is longer because frames have become a lot 
longer the front center has become longer that's   the main difference on the first part of the frame 
we're going to work on the bottom bracket shell   and i've got one here i've got a hole and i've 
got a couple other little holes i'll explain that   this one here is a it's a richie bottom bracket 
so the first thing we're going to do is to make   a hole i have two holes here this one is for the 
it's for the down tube if there's any any any any   moisture that gets in through the water bottle 
bosses or something like that it lets it out   and these two holes are for the seat tube because 
if you get watered down into your seat tube it has   to go somewhere because otherwise the water will 
sit in the bottom and it'll rust out the holes   so let's go over to the mill we're going to 
make a hole we're going to center the hole saw   we're going to put a hole in there for the down 
tube and then on the on the drill press we'll   drill two quarter inch holes for the seat tube i 
got a 7 8 hole saw here because that's the size   this is i could go inch but 7 8 is a little bit 
safer because the down tube is inch and a quarter there you go i'm just going to go right through with a center 
drill you're not really supposed to do that but but i just did i have a down tube it's it's tangy it's prestige 
very nice it took me a while to find this   and now i need to know where where the 
butts are inside so there's going to be   a long butt and there's going to be a short 
butt that's usually what's what happens and   then in in the middle is the thin section and the 
tapered sections that's the inside of the tube   i have a butt detector it's even labeled as a 
butt detector what this does i hold it in the vise   and then it's got a dial indicator here when 
that needle goes down that's the end of the butt   see that see right there that's the end of the 
butt so that's where i make my mark right there   then i do the other side it's 
going to be interesting to see   if the butts are the same 
or one's longer oh see that definitely shorter so it'll go down 
and then that's that's where the   the straight section starts right there 
so you come along on the straight section   there's the tape and that's the taper happening 
and then that's the butt so the butt ends right   right there obviously this goes down onto 
the bottom bracket and this goes up to the   head tube because there's a lot more force up 
by the head too when you hit an object or you   bounce off a curb this is taking more shock so the 
longest section i always put up to the head tube   so we're going to miter this now we're going to 
miter this inch and a half and then that's where   the bottom bracket goes on when we were building 
frames this piece here was always on the mill   when you put a a tube in here when you see 
an equal space underneath you know that the   tube is level because you could easily hold 
it like that or you could hold it like that   and and not know that it's not level so what we 
do then is is to put spaces under there like that and now if you look that air gap should be level i go through nice and slow and then it 
won't leave a little bump on the very bottom always use a pair of pliers it's such a 
temptation to want to use your fingers   and then you cut yourself i know because 
i've done it do you see how shiny that is   i can braise over that but i think it's 
way better if i put a cross hatch on there   so this has been made with an old 
an old motorcycle disc brake or   rotor and this piece of angle iron got 
welded onto the bottom and what this does   you put the bottom bracket on there this is also 
68 millimeters so you center it with your finger   fingers and then you put the tube on like that 
and then you center it now this here is a little   little guide to save time 
don't have to use a vernier   or anything like that and what this does it holds 
the tube in place for when you when you tack it   so down here you see where the holes 
are you need a little little little   bit of a gap there what have i got a couple 
millimeters there i'm talking metric to you   i've got a couple millimeters on each 
side i have to take this off i have to   flux it because i can't flux in the back 
and then i can get a nickel silver tack   nickel silver tack then i'll put it into the 
park stand and i'll nickel silver around this   is that blue it's type b paste flux from the el 
raya gas company in el raya ohio it's good stuff   a lot of frame builders use this if this is the 
cone of the flame if i hold the cone right there   it heats up the bottom bracket and the down 
tube at the same time and then i put a little   tack there that's where i want the cone to be 
i don't need to do a big preheat back and forth   just right there that's the right that's the right 
spot this is the first step of building a frame there we go so we've got a little tiny tack 
there maybe not super tiny but so i flip it   round and i do the same thing here yeah the 
bottom bracket took a little longer that time   put more heat on the bottom bracket it's a 
little thicker tube so i've got the torch maybe half inch away maybe 12 millimeters and i'm aiming the heat a little 
bit more at the bottom bracket   because it's easy to overheat the tube there we go so we'll just let that cool down we're at the frame drawing now and 
this is going to be the seat tube   extension this is what we use this 
is a piece of chromoly it's 4130   it's pretty thick wall it's got some weight 
to its 0.95 wall but it gets machined down   this is where that goes so we've got a a two 
inch segment here we've got a three quarter   inch segment up there and so we we need to go 
to the lathe now we're gonna machine this out nine nine six that means that one end 
is point nine millimeters and then it   tapers and then it's point six that's how 
all seat tubes used to be then in the 90s   we got the bulgebot seat tubes where it had 
the bulge out here it was an external butt   and you didn't have to add the extension 
anymore that was a big a big plus for the   frame builders so let's have a look and see where 
this butt is can you see how the needle goes down right there that's where the butt ends we'll check the other end because it 
probably doesn't have any butt at all   see that's perfectly straight i could take off 
a little bit more of the butt because then i   would save a little bit of weight on the frame so 
maybe i'll do that make a hacksaw mark right here   and this hacksaw cut is going to be right there so 
i'm marking it right about there because this tube   is going to go into the seat extension about a 
quarter of an inch so let's go make a couple cuts let's go to lathe i'm going to face 
this end because that's going to go   into the seat tube extension we want that to be 
perfectly flat not at an angle from a hacksaw so this is the seat tube extension 
we've got a boring bar here so we're at minus oh minus one so this 
should fit now let's see what happens   there we go and that's good because look it's 
got a little bit of play if it's too tight   it's hard for the nickel silver to flow so you 
can you can tell there's a little bit of play   i'm going to call that good so if i was just 
to hold this in the vise and put that in it   could end up at an angle because see i've 
got movement so this is what we used to do   this is this is what holds everything in place 
so i've got my my little little drill press vise   and then this slides down over top so it's 
it's got a little bit of play but you know so we need some flux i want to make sure 
the flex goes inside there we go so that's   seating all the way down a little bit of flux 
everywhere so what i think i'll do is i'll   i'll put a few little tacks around it if i just 
tack it on one side and start to braze it's going   to pull so it'll be less obviously of the pull if 
i tack it in three spots and then braze around so   i've got a fairly hot flame here let's see if it's 
too hot oh can you see that it went it went in so it's good to have this warm because the nickel 
silver has to go down one quarter of an inch   and that's capillary action that's when 
the heat is pulling the filler material   in that's how lugs work there we go we're done i've soaked off the 
flux so now you can really see all the nickel   silvering it's fairly smooth so i've got my fancy 
alignment gauge we're going to check and see   how true the down tube is off the sides of the 
bottom bracket now so what i'm doing is here i've   got one hand on the alignment tool and the other 
hand is on the other side of the bottom bracket   and so i'm putting on pressure and we'll 
get it there we go we're very very close   so we flip it over okay so it's out a little 
bit so we need to pull it it's going to be   pulled and this is pretty normal because you're 
putting heat on one side then on the other side   i've got my bottom bracket cuts these are fixed 
cups from years ago and all the threads have   been ground off so just give it a little 
bit of a pull you can see the tube flex so we've got a little gap there and we've got a little gap there so there we go 
that was one pole and that's close enough so it   didn't take huge amount of effort it just took 
a little bit of a pull so what we have to do now i'll grab the head tube inch head tube inch 
and a quarter down tube can you see how they're   basically the head tube is a touch larger 
so if you philip braze that that means   there's almost no material there so 
this has to get ovalized this way   i've got this held in the arbor press now it's 
the weight of the arm that's holding everything   so what i want to do is to make sure i got 
the bottom bracket vertical so see i've got   an alloy plate here and i've got an alloy plate 
here so if i eyeball this i can see it's out a   little bit so if i hold my hands like that 
there we go that's my icrometer i'm using   okay i'm happy with that okay so 
here we go we're gonna ovalize it and you can see it come it springs back 
that's because it's 4130 and it's got   memory it definitely is a tough 
metal a little more there we go overpress is very handy for frame builders so 
there we go with ovalized it's a it's very nice   there's no no steps no transition of well very 
smooth transition let's look at the head tube now   so there we go we've got an 
eighth of an inch on each side   and if if you want to take out a little bit of the 
ovalization we don't have to have quite that much   you give a little squish and and the memory 
will help it to come back there we go i just   opened it up a very tiny amount so there we 
go there's our eighth of an inch on each side   that's perfect for philip brazing i've got the the 
bottom bracket and the down tube on the drawing   you see how i've got the combination square right 
in the corner and then i press down that's where i   mighta and that's as accurate as i can get because 
i'm going oops yeah i'm going off the drawing so we've got the angle set it's 23.5 degrees 
we'll go to the mill we'll set the angle up   and then the hole saw is going to get edged up 
to that line remember this level piece here this   is where the bottom bracket sits on it's what 
holds the bottom bracket perpendicular to the   miter at the other end so you can loosen 
this because there we go so now it's down   and it also happens to be spaced just right 
that's how this was designed so that when you   put a frame a down tube and a bottom bracket on 
here it's holding it perpendicular to the miter yeah so what i'm doing here is i'm i'm 
going to check and see if the seat tube   is bent because it's being braised 
halfway so that's the low spot right there   so we'll make a mark and then that's the highest 
well didn't stay on the zero that's the high point   so when i ovalize this i'm going to 
ovalize it this way and it's going to be   this is going to be on the top or the bottom it 
doesn't matter you can ovalize it well that's a   pretty strong tube you can feel it it's only 
0.9 millimeters but there we go i like that so we squish that because it's it it widens 
the tube a little bit at the bottom bracket   makes it a little easier for the philip 
brazing so we're matching up there and then you're going to 
miter right about to there   if the seat tube's a millimeter longer 
or shorter it's really not here or there how do you mark the middle of a tube well if i 
make some assumptions that the floor is level the   vice the the work bench is level the vice is level 
then if i hold the ruler level hold it at a 45 that is the center of the tube so if i take a 
felt pin i don't know if you can can you see   that mark it's just a little scrape but if i 
mark it like that so i've got a felt pin mark   i've got an extrusion here nothing fancy 
if i put that on like that and i line it up   there you go i just found the middle of 
the tube it wasn't rocket science at all what i'm doing this for is to mark 
where the water bottle bosses go   so seven inches is right there 
and then we want 2.5 inches do you see how it indented just a little bit   i force the tubing in that 
helps the center drill to start we have the frame jig here i'm going to take 
some measurements off the drawing and we're   going to set up the frame drag frame jig for this 
particular bike this romax every frame builder   has a different jig sometimes i made all my own 
years ago so if i loosen that i can slide this   that is the front center and then this is my head 
tube angle so if i lock this a bit it'll hold it   so this is metric here i'm going to measure 
what the front center is 665 millimeters   we'll set up the jig for that 62 64 66 so 
665 is going to be right right about there so i'll lock that a little 
bit then we set this to 70.5 that looks good there this is the drop we got 
all the measurements there there's my drop it's   uh it's a little over four a little bit over 
there right there and then the seat tube angle 74.   so on the fork we went axle the crown then 
we added in the stack height which is the   lower headset now we need to measure from 
the axle up to the head tube we're at 407   that's what it looks like to me that's 
your axle right there we need to go 407   and that's where the head tube goes to 
right there so this has to come down that looks good four o'clock 
i can see four or seven there   so that'll work i've got a head tube we have to 
cut the head tube to the same size as the drawing   and hacksaw and then face it in the lathe then we put on the bottom bracket and 
the down tube and you see how it fits sometimes you have to move 
the jig around a little bit not bad not bad for first try so what we 
need is a quarter inch gap at the bottom   so we have to move the jig back just a touch moved it back maybe a millimeter there we go and 
that's a pretty good fit there it's not much in   the way of gap there i could take a file and i 
could fine tune it just a little bit but that's   not bad at all for first fit what i need to do now 
is to is to file i need to notch the seat tube if   i was doing a run of 10 frames i'd set it up in 
the milling machine but for one i'm just going to   file it by hand because it doesn't take that long 
so you can see how the miter at the back there's   a big gap what we want to do is to file that so 
that that comes in and it sits right on top and   there's no gap on the front let's see if we can 
accomplish that so i think we're basically good so here we are here's this 
is the length of the top tube   and what i like to have is 
longer but here than here it looks like that's what suits me right there so   up by the head tube we're going to have about 
this long and you can see how this one is shorter   so i'm going to make a mark 
here that's my hacksaw mark there you go h for hacksaw m for mitre and then 
we'll figure out this we'll we'll have to cut   a little bit off of this end so first of all 
hacksaw and miter and the miter is at one degree so we mitered at an angle of of one degree 
so so that's not right see see this this   end of the top two needs to end up 
in the middle so we'll flip it over and it still doesn't look quite right it needs 
to come up so let's change the angle of the miter   make it make it two degrees i think move it in 
a couple foul take a very very small skim cut okay so look at that it's right in the middle 
now so that's good this little holder here   it puts the top tube in the right 
position because something has to   hold it up so there we go that's what i want 
maybe a touch higher just a little bit higher   because we want a space there of one quarter 
inch okay now i'm going to mark this tube   off the drawing so what i'm doing is 
i place it on the drawing like that   i put this into the mitre and i line it up with 
the head tube that looks good and then i set this   up in the corner like that and then i make a mark 
and that's my motor mark and that looks good so i   need to just do a bit of sanding around all the 
places that need to be braised and then we can   tack it up so i have a sequence here i always i 
tack here so one two three four underneath five   and six that's what i do and there's a reason 
for that i will explain shortly probably next week so we line up the bottom bracket and the head tube so there we go it's lined up and then 
what you want to do is to go around the   other side and you look at the seat tube if 
the seat tube is lined up with the drawing   then that's good and i can tell from 
right now that it looks pretty accurate   i'm happy with that if the bottom bracket's lined 
up in the head tube that's what you're looking at   and i think we've done fine that's all 
we have for right now our time has run   out thanks for joining us next week we'll be 
doing philip brazing filing braisons alignment   all that so hope you hope you can make 
it thank you stay safe have a good week

As found on YouTube

Extremely light racing helmet >

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Related Post