Steff's xs #6 King Queen Seat...

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Prof
Founder, Choppers Australia
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Steff's xs #6 King Queen Seat...

Post by Prof » Sun Oct 28, 2012 11:38 pm

Steff has asked for a King and Queen seat and we are only to happy to oblige, being rather keen on the Classic chopper of the early 70's and all that!

I have done a series of posts on this subject some years ago, so I think now is a good time to do it again.

I use 3mm aluminium for my seat bases. I prefer ally to steel because it is lighter and stiffer.

Step one is to measure the widest part of the seat, For the width, I like to show about a third of the frame on each outer edge.
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...and draw up a rectangle that width and then put in a centre line.
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Next is to measure and mark length of rider seat and then grab a piece of paper and draw up the curve of the front of the seat on on side.
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Cut it out and draw it onto the ally, turn it over and reapeat. You now have matching curves on the front. You can see that I have only traced on the curve. The straight section is measured and drawn in with a ruler... this keeps everything even.
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Now for the rder back rest and passenger seat base. A bit of thought and playing around with the tape and ruler is needed here.
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there is nothing worse on a ride than having your passenger continually slide into you. Make your passenger seat base slope back slightly. Half a spirit level bubble works pretty well.
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Mark the lengths of rider's seat back (left) and passenger seat base. For best looks the seat back should narrow towards the top and the passenger seat base should narrow a little towards the rear. Measure and mark in these widths...
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Passenger back rest is a bit tricky to mark because the actual bend in the aluminium will be a bit past the support, so I do one measurement from the level of the support up the sissy bar a couple of inches and then do my final measurement (which gets added on) to what will be the highest point of the backrest.
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Measure the width at what will be the beginnning of the top curve and mark this onto the ally. Now I initially decided to do a slight ogive shape (pointy circle) rather than just a round top, but then went back to a round one. To do an ogive as shown in this pic, use a sharp dividers to mark the curve. the centres of each arc will be to the side of the centre line. the further apart the two centres, the pointier the ogive. To do a circular top as I ended up doing (not shown), the centre of your arc will be on the seat centre line.

No doubt you have seen photos of classic choppers with passenger seats only as wide as the guard (ie 6") Well if your passenger likes sitting all day on a six by six post have a narrow seat like that by all means, other wise be a bit kind to her and give her something decent to sit on.
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Time to cut it all out. Angle grinder with 1mm blade is best. To stop it grabbing, regularly push candle wax against the sides of the blade. Curves are cut with a series of 'plunge' cuts.
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Clean the ragged edges up with a coarse file. File an arras on both sides of the cut to reduce the sharpness so the vinly or leather does not get cut on these edges...
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Cleaned up ready to bend. Ogive has not yet been modified... was done once seat was on the bike and inspected...
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In the folder with one bend to do. A couple of pieces of heavy duty 2" andle iron in a vice and held by a stout G clamp at the other end works fine, but takes a bit of time to set up. Use a hammer to progressively bend the ally being careful not to put big dings in it!
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Set up on the bike for inspection and measuring of the rear locating holes...
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A step drill is a great way to cut the holes to size and get them nice and round...
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If you look closely at this pic you will see two changes I have made. The riders back rest was too upright and put the rider a bit too far forwards and the passenger seat ended up a bit too long. So I have cut the aluminium at the front of the passener seat, overlapped it 20mm and welded it (no charge Steff, my mistake). If you need to do this riveting si quite satisfactory, but welding is quicker and stronger. This has allowed me to put a further bend in the riders back rest for a better angle.
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A pattern of the sides is made. About a 4mm gap is left between the frame and the bottom of the sides so the seat covering doesn't rub.
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Sides cut out using a nibbler. These are great for thin material and intricate shapes but a real pain to keep on the line. Two hands are definitley needed, but i had to hold the camera with one for this shot!
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Folding the sides in the vice with hammer. Front tab has been cut in two places to fit the curve of the seat back...
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Riveted in with 1'8" (3.2mm) rivets. These sides play a big part in keeping things rigid so use plenty.
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Usually to locate the front of the seat a tab would slide under the gusset, but in this case the switches are in the way, so I will cut a slot in the top of the gusset and make a z shaped tab to attach to the seat. Two holes are drilled and files or die ground to produce a slot that is a close fit on the tab... you don't want the front of the seat wobbling form side to side. I should mention here too that I always try to make seats quick to remove if a battery, oil filler or electrics need to be accessed...nothing worse than trouble shooting in the dark and spending an age just getting the seat off!
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Front tab could be riveted directly to the seat base, but I prefer to have it removable if only for convenience to the upholsterer. Here you can see the tab has been made and drilled to 6mm and a second plate that will be threaded and riveted inside the seat is being marked for drilling. As the holes need to be smaller than those in the tab so they can be threaded, I am using a 6mm drill bit to locate in a small depression I have already drilled using a 6mm bit. Once both depression have been made I can then run a 5mm bit through and thread the plate
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Inside plate tapped and riveted in place on the inside of the seat base. Tab has been bolted on so the bolts can be cut to length... you don't need them wearing through the padding...
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The seat is locked in place by an 8mm bolt near the top of the passenger backrest. Once agian a threaded mounting plate has been made. Because it is 6mm thick I have counter sunk the rivet holes so they don't protrude into the back reat padding too much.
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Seat base finished. You can just see the front tab. Try upping your computer magification to 2 or 400 for a better look..
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Padding has been done and we will show you some pics shortly...
Chopit'nrideit... Prof

Aussiehard
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Re: Steff's xs #6 King Queen Seat...

Post by Aussiehard » Mon Oct 29, 2012 8:41 am

I get some cheap fuel line with a scalpel slit one edge and trim the edge of the sheet metal so it has a larger radius and cut cut through when covering the set.
Here are some of the photos from my blog article on doing it.
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Silent Grey Fellow
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Re: Steff's xs #6 King Queen Seat...

Post by Silent Grey Fellow » Mon Oct 29, 2012 10:52 am

Great looking seat Prof
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Silent Grey Fellow

Prof
Founder, Choppers Australia
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Re: Steff's xs #6 King Queen Seat...

Post by Prof » Mon Oct 29, 2012 1:43 pm

Thanks for your pics Aussie.
Ialso have trim that fits, but it does then lift up the seat off the frame a bit and makes it harder to set up. Cheap rubber hose is a good alternative. In the past I used to use medical plaster about an inch wide... that also worked well, but with this kind of seat I haven't had any problems as long as the sharp edges are removed.
Chopit'nrideit... Prof

Prof
Founder, Choppers Australia
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Re: Steff's xs #6 King Queen Seat...

Post by Prof » Thu Nov 01, 2012 9:41 pm

Padding Steff's seat...

There are a number of padding options, but I've not found anything as comfortable and long lived as 'consolidated' foam... made in various wieghts. I buy it in 2" and 1" slabs. Consolidated foam is far surperior to high density foam. It has 'life' or 'spring' in it year after year after year. HIgh density foam is dead and compacts quickly. Motorcycle seat upholsterers also use a moulded product, but I am really happy with what I use... and it is easy for anyone to do if you can measure and use a sharp knife... and know a few of the tricks specific to this activity.

Padding is made up of a number of separate pieces glued together and to the seat and then shaped with a knife and finsihed with an angle grinder. In the case of a king/queen seat, there will be one 2" piece for the rider seat, a 1" piece for his backrest, atwo pieces; 2" and 1" for the passenger and a final 1" piece for the passenger back rest. A small triangular piece will create a smooth transition between the rider seat and back rest.

First step is to trace the shape of the first piece. Note the TWO marks on the left:one where the bottom of the foam meets the sloping backrest and one where the top meets it. The foam will be cut at an angle along this end.
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Consolidated foam cuts easily with a sharp knife. I use the serated blade of a diver's knife... a narrow blade will drag less than a wide one. The most important things to remember are firstly to separate the foam easily as you cut to prevent drag. In this pic you can see I am cutting the foam on the floor and holding the foam with knee and foot while my spare hand gently pulls the foam apart. Be careful to do it evenly or your cut will be ragged or crooked.

Secondly, take care to keep your knife vertical or you will end up with an angled cut and the foam will not cover the base. It is a good idea to cut your foam 5-8mm wider than the seat and trim it back afterwards. If you do end up cutting the foam too narrow or short you can stretch it when you glue it, so all is not lost.
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Once I have rough cut out each piece of foam, I am lucky enough to have a bandsaw on which to do a final neat cut.
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First two pieces cut. Note the angled cuts because f the angled seat back...
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Five main pieces cut and ready for gluing. I do not glue the join between the passenger backrest and the passenger seat foam, because the weight of the pillion will want to drag down the backrest foam and be just that bit harder at the base of the pillion's spine. For the same reason I try to get the upholsterers to include a tuck along this line so the vinyl/leather of the back rest is not dragged down by the pillion's wieght.
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The pillion backrest and rider seat are relieved with an angle grinder so the foam fits comflortably over captive threads...
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I use Selleys' Quikgrip contact adhesive. It is very strong once set. Don't buy large tins as the glue dries up once there is air in the tin. I spread the adhesive with my finger protected by a rubber glove... Quikgrip is a poin to remove... petrol being the only solvent I know. Better not get it on your hands in the first place... Selleys also make Gelgrip... it is not as strong.
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Spread adhesive evenly on both surfaces (seatbase and foam) and leave until dry to touch. CAREFULLY line up one edge and push that edge of the foam down onto the seat base. Line up the opposite end and do the same, without putting pressure on the middle. If you are careful you can then line up the sides and press them down. Once contact is made, the adhesive is permanently fixed... takes a bit of practice, but you CAN get all four sides lined up and stuck down. Once all lined up and pushed onto the base, use a wide mallet to hammer the foam onto the base and make a very permanent join...
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If you look carefully at this pic you will see the line of the glue on the left, about a quarter of the width. No need to cover the whole area with adhesive. I run a small fan across my work table to blow the unpleasant and quite toxic fumes form the glue away from my face...
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Five pieces of foam glued to the seat base, plus a smalll triangular piece for the rider. Rider now sits on seat to test it (will test it a number of times to get it comfy) and see if any modifications are needed. You con't want any pressure points. Rider's seat base has also been trimmed at the front with a knife to prevent pressure on the rider's inner thigh muscles. More gets trimmed off and later ground off.
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Front of pillion seat marked...
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... and trimmed along with a bit more of the rider's seat trimmed...
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Now out with the angle grinder to smoothly contour the seat. Not so easy to see, but I wear a respirator as the fine foam really gets into the lungs if you don't! Practice on some scrap foam, before you do this operation. You need to be aware of the grinding wheel's rotation at all times so it doesn't grab and dig into the foam or tear the edges...
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Seat finished and all edges rounded. Note the trimming that has been done at the front of the rider's seat...
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Another view...
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To finish the seat, I glue on a thin layer of softer foam. This makes for a nice smooth finish and also gives a nice soft layer. I'll put up a pic when I have done this.

Steff has an upholsterer who will do the final vinyl or leather cover, but just a couple of comments. Don't run a bead around the edge unless you like cutting off the circulation in you legs! Vinyl can be slippery especially as it ages, so it is wise to stitch in a pattern... swirls, bars or diamonds. Don't use buttons... they create hard spots that become very annoying on a longer trip. Under your seat cover run a layer of plastic to prevent water getting in at the stitching and and soaking the foam... annoying and embarrasing the day after rain when you get off your chopper with wet patches on your pants!

When making your own seat, put a temporary cover (panty hose work great!) on the foam and ride the bike for a week in case you need to remove a bit of foam.

I've not personally run a leather seat as I ride my chopper constantly and often in rain and frequently all day in the saddle. Any comments from those of you who do a lot of miles in all weather on leather seats would really be appreciated.

As I have said many times, a righteious looking chopper is not necessarily a righteious riding chopper. But you can have comfort AND looks. If you want to do lots of riding... take care at this stage to make your seat comfortable as you can within your overall design.
Chopit'nrideit... Prof

Bearcx
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Re: Steff's xs #6 King Queen Seat...

Post by Bearcx » Thu Nov 01, 2012 10:20 pm

Very helpful pics, thanks Andrew. Lookin the goods. 8)
The brave may not live long, but, the cautious do not live at all.

Silent Grey Fellow
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Re: Steff's xs #6 King Queen Seat...

Post by Silent Grey Fellow » Fri Nov 02, 2012 3:08 pm

Fantastic job Prof it is really starting to take shape now
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Silent Grey Fellow

eddiehob
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Re: Steff's xs #6 King Queen Seat...

Post by eddiehob » Sat Nov 03, 2012 3:44 pm

Nice Job Prof ,I enjoyed this post as i am planning a similar seat ,Was very useful to me .
Cheers

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