Just thinking - maybe someone can verify (or clarify) my thoughts -

If one is reducing or enlarging pieces on a copier that have no seam allowances, the result should be what one wants.

If one is reducing or enlarging pieces on a copier that INCLUDE the seam allowances, should one remember to modify the seam allowances to 1/4 inch? (Because the seam allowances would also be enlarge)

Enlarging Example: If I have a pattern piece that is 4.5 x 8.5 - and it finishes to 4 x 8

and I want to double it to finish to 8 x 16 - I need pieces that are 8.5 x 16.5 - ???

But if I DOUBLE the original piece on the copier, it will result in a patter that is 9 x 17 - which would not work out well.


Reducing Example: If I have a pattern piece that is 8.5 x 16.5 (finished size 8 x 16) and reduce it by 50% - that would give me a pattern that is 4.25 x 8.25 - and it should be 4.5 x 8.5

So then I would need to ADD to the seam allowances? because the reduction would have also reduced my seam allowances.

Or would it work to just enlarge/reduce the pattern pieces and correct the seam allowances to 1/4 inch ?

Here you go:

http://www.thequiltedsnail.com/scale.html

Maybe this will help you out.

A copier is usually used to change the size of pieces for applique, but not usually for pieced blocks, for the reasons you mention. What exactly are you trying to do, and perhaps then we can offer more help?

You're correct in that your percentages only apply to the finished size of whatever it is you're enlarging.

After you've enlarged it, THEN make sure you have a 1/4" seam allowance.

So if the picture is a 4.5" snowball block (which would finish at 4" ) and you want a finished 8" snowball block, then increase by 200%.
The seam allowance will be too large - it doesn't matter what it is. It also doesn't matter if it goes off the paper.

Just that you measure, mark and cut it at 1/4".

I don't know if you're talking about paper piecing or machine piecing or applique so that's why I'm using the Snowball as an example.

If you were cutting templates, then you would cut the enlarged finished size from the paper, and when you cut the fabric, you'd add the 1/4".

Make sense?

I would take the 1/4" seam allowance off, reduce or enlarge, then add the 1/4" back on.

That sounds correct to me. :D

On my printer, I don't use quick print. I use settings. You can enlarge or reduce from there. You might have to reposition the page to get all of the pieces enlarged.

You are correct that reducing and enlarging with seam allowances mess up the seam allowance.
So, best to do the adjustment without and then I would redraw the design on graft paper to make sure the enlargment or reduction is correct. Some copiers distort alightly. I don't see how you can get around redrafting.
I sometime use the copier to at least get the approimate size and then hand draft

I work at a copy shop. There can be a slight variance from one copier to another. I would always enlarge without the seam allowance. As far a programs that you can use, I would see if there is any shareware that does shapes. I am making a GFG and found a site that I could print hexagons. I will see if I can find that site and pass it on.