In need of some sewing pattern advice Brat Style Seat on CB750

[hlewis12]

One of the last things that I need to do in order to finish up my bike is to make a seat cover. I've made the seat pan out of 16ga. steel. Foamed is with a couple of different materials and ordered vinyl and started trying to make the cover. One disclaimer is that I've only sewn a couple of things in my life and I'm using a home sewing machine with a walking foot that came from my grandmother. I purchased the vinyl and thread at sailrite.

My general plan for the cover is something along these lines.

I found these pictures online.

I think I'm going to go with more of the top image that does not have the border all the way around the pleated parts.

This is what I have so far.

This is not sewn together but I did try this and I could not get the material to lay properly.

I need advise on how to cut the rear section so it will lay smoothly. Should I be using just a straight cut piece of vinyl and follow the curve downward on the side of the seat or should I use a curved boxing as seen in the picture above or should I actually cut a piece of vinyl that follows the contour of the rear part of the seat similar to how the pattern below was done. And I may need to make it in two pieces. I just need some advice from someone who has done this before. Thanks in advance.

Here is the bike that it will eventually go on in the mock up stages.

 

[dieselchanic]

I haven't done one in that exact style, I usually put my seam right on the edge of the curve, so I don't know if I can be of much help.

What I would try is making that back piece so it would sew on vertical, or at right angles, to the main part and then curve it down at the sides. With the seam being a little over the edge, sew it a little small. The vinyl will stretch quite a bit and result in that curve. Trouble with getting it too tight is that it will likely pull the pleats down. I also try to sew another piece on the bottom of the pan with a seam at the edge so when the seat is viewed from the bottom everything lays flat. Keep in mind that I am just a garage builder using a common sewing machine and literally have no idea what I'm doing, simply trial and error up to this point. Here are some I've done.

 

[dieselchanic]

Here's a pic of what I'm talking about on the bottom and how that seat fit the bike.

 

[kosmjon]

Glad to see others trying to tackle this as well. Looks like you are off to a great start. I have only done a couple of small samples so far so I can't directly answer, but I wanted to pass on this great video I found that helped me a lot: https://www.youtube.com/watch?v=8nVyPiPvR2g

 

[hlewis12]

Those seats look great. I think I understand what you mean by doing it at right angles. I think you mean to do it like in Figure A below correct? Then I would just start sewing at the center and work my way out to the left and then right side pulling the fabric flat as I sew.

 

[hlewis12]

Glad to see others trying to tackle this as well. Looks like you are off to a great start. I have only done a couple of small samples so far so I can't directly answer, but I wanted to pass on this great video I found that helped me a lot:

I used that exact video to figure out how to do the top pleated section. And I ordered all of my material from Sailrite which made the video. I could just make the border all the way around and follow the video exactly but I'm stumped when trying to make the downward curved section.

 

[dieselchanic]

Yes, figure A is what I was meaning. It will seem like it won't work and you'll want to scrap the whole thing, but test fit it anyway... I almost completely give up on most of mine then somehow they actually turn out.

 

[mathil]

Usually when patterning out a seat its easiest to get some clear plastic to draw on with a sharpie.

Finish your foam shape how you want it, and draw where you want your seams to go on it. Lay your plastic on, and trace the seams on to the plastic. Add your seam allowances and sew away!

If there's sections where the plastic needs to be pleated excessively it's good to break it up into separate panels. You can either make the cover too small, and stretch the material, or you can make it perfect and use more panels.

 

[crazypj]

Cool, thanks for posting that.
It's the most useful idea I've seen in a long time

 

[hlewis12]

Yeah absolutely some good advise on the upholstery. I did some more work on the seat yesterday. I'm not happy with the results but its good enough for now. I have enough material to do another cover and I may either do try again or I may have a shop do it for me. I've been working on the bike for almost a year and I just ready to be done and ride some before it gets too cold. All of the riding I've done up to this point has been on the steel seat pan which was not that much fun. Anyway here is a pic on the bike. You can see where it is loose in some areas around the curved section.

 

[mathil]

That's a good step in the learning process.

When making the cover you need to factor in the strechability of the material. It should be stretched, not too much, not too little, there's a Goldilocks zone. Stretching the material takes care of all of the little waves and unevenness. If you stretch too much you'll run into other aesthetic problems though, so a little experimentation is in order.

For instance, When I'm at work I sew a cushion that's about 50" wide. The actual piece of foam I stuff in there is 52" wide, otherwise it looks saggy and floppy. Nice precise stitching with a good amount of fill will make a good product every time.

 

[hlewis12]

I'm planning to use rivets to permanently hold the cover on. In the pictures I basically have the seat cover stretched over the pan and foam. I think I will to do as you suggest and add some more foam over the padding that I currently have in order to fill out the vinyl a little more before final riveting. I'm glad you mentioned that about over sizing the foam because I definitely did not think of doing it that way.

 

[mathil]

A lot of times the hard seat foam is shaped to desire, and then a softer fill foam, or fluff, or whatever you want to call it, is put in right under the cover.

This will fill the cushion out, but be warned that it'll poke out and make bumps out of any of your stitching inconsistencies.

 

[jvandyke]

I'm starting down a similar path and wonder if you can't just wrap the whole thing with the pleated top panel and forego the side panels?, I suppose at some point the transition from vertical side to horizontal top is too sharp to wrap, I would soften the curve? I'm making a brat seat and want the same brown pleated look but hope to do a full wrap, because that's easy, (I would think)

 

[DeanJ]

Vinyl is pretty stiff and unforgiving, so seams don't like to go around curves, thus causing bagginess. So for the side to back panel seam, I make mine straight. I keep the relationship of the side panels oriented 90 degrees to the top panel. This really helps when you are fixing the cover over the foam onto the pan too. btw Leather is MUCH easier to work with as it can take the shape of curves and contours when stitching and when mounting.

this is my straight seam for angle transitions:
http://www.dotheton.com/forum/index.php?topic=62814.msg722138#msg722138

 

[mathil]

Vinyl is pretty stiff and unforgiving, so seams don't like to go around curves, thus causing bagginess. So for the side to back panel seam, I make mine straight. I keep the relationship of the side panels oriented 90 degrees to the top panel. This really helps when you are fixing the cover over the foam onto the pan too. btw Leather is MUCH easier to work with as it can take the shape of curves and contours when stitching and when mounting.

this is my straight seam for angle transitions:
http://www.dotheton.com/forum/index.php?topic=62814.msg722138#msg722138

When I install covers I put them on a space heater to warm them up. You could use an oven, or a heat register, or anything really.

Good vinyls can be soft. Cheap vinyls are hard and crack at 10C.

 

[hlewis12]

Vinyl is pretty stiff and unforgiving, so seams don't like to go around curves, thus causing bagginess. So for the side to back panel seam, I make mine straight. I keep the relationship of the side panels oriented 90 degrees to the top panel. This really helps when you are fixing the cover over the foam onto the pan too. btw Leather is MUCH easier to work with as it can take the shape of curves and contours when stitching and when mounting.

this is my straight seam for angle transitions:
http://www.dotheton.com/forum/index.php?topic=62814.msg722138#msg722138

First and for most your seat looks great. Secondly I'm super jealous of your sewing skills. Last but not least confused by what you mean here, "So for the side to back panel seam, I make mine straight. I keep the relationship of the side panels oriented 90 degrees to the top panel." I think that means for the side and rear sections you cut 3 rectangular piece's of fabric and sew them to the top panel at 90 degree angles and then after they were attached to the top panel (obviously the three side panels had to overlap a little) you go back and sew them together pulling the back pane to a 90 degree angle so it is now perpendicular instead of horizontal with the top panel as shown in your picture below.

 

[DeanJ]

The finished side panel ( 3 pieces) is indeed sewn at 90 degrees to the top panel when fitted to the seat pan. Go back and look at the wood seat pan and you will see that it is not flat, it angles up at the back . The angle the individual side panels are sewn together to match the top when angled may be confusing, yet allows a simple 90 degree seam when attached to the top.

http://www.dotheton.com/forum/index.php?topic=62814.msg720739#msg720739