TOPIC:

Here’s a scrap of the aluminum spacer stock that a suspension company sent me when I ordered new springs. It measures 1.3 mm thick. The spacers were approximately four inches long each.
They told me I could have used schedule 40 PVC as well.
 

It's been a while, but I'm pressure sure Sonic Springs includes a hunk of PVC pipe with their fork spring orders.

a question came up recently on another site, I answered with this:
"regarding the PVC fork spacers, pipe is available if different wall thicknesses - that size is referred by schedule, or 'sched'... sched 40, sched 80...
However, "ABS pipe - ABS stands for acrylonitrile butadiene styrene - its properties are "Tough, rigid", ABS piping has a higher impact strength than PVC...
ABS is highly durable with high impact strength.
PVC is less durable, as it is designed to be flexible and softer than usual plastics. However, both plastics are resistant to chemical and water degradation...
ABS is also used to create musical instruments, golf club heads, car bumpers, protective headgear, whitewater canoes, luggage, kitchen appliances and toys, including Lego. It is also used as a colorant in some tattoo inks..." www.diffen.com/difference/ABS_vs_PVC

sizing:
3/4" Sched 40 has an OD of 1.05", 0.113" wall thickness
3/4" Sched 80 has an OD of 1.05", 0.154" wall thickness
plasticranger.com/abs-pipe-sizes-dimensions/

Nessism wrote:

As long as a steel washer is used between the PVC and the spring, there is no need for a steel spacer.
 

If using a standard flat washer, see sizes here:
SAE Flat Washer Dimensions & Specifications

www.aftfasteners.com/sae-low-carbon-stai...chanical-properties/
 

I’m in the process of rebuilding a set of forks for my Zephyr 550, and I got new springs from RaceTech. But the ABS tube they gave me to make spacers from is not long enough to cut two equal-length spacers. I found an old Trek composite bicycle with a carbon fiber top tube, cut the tube off (the rest of the bike was damaged anyway) and it fits my fork ID better than the tube from RaceTech does. So I plan on using that after I find a way to cut it straight and accurate. 

Stereordinary wrote:

I’m in the process of rebuilding a set of forks for my Zephyr 550, and I got new springs from RaceTech. But the ABS tube they gave me to make spacers from is not long enough to cut two equal-length spacers. I found an old Trek composite bicycle with a carbon fiber top tube, cut the tube off (the rest of the bike was damaged anyway) and it fits my fork ID better than the tube from RaceTech does. So I plan on using that after I find a way to cut it straight and accurate. 

If you raw cut the tube, using a fine tooth hacksaw, then use a piece of tape, around the tape to mark the proper length, a bench grinder stone can be used to dress the raw cut back to your proper line.  Try not to breathe too much of the carbon dust.  If a cloud develops, back off and wait for it to clear.

A carpenters chop saw with a fine tooth blade will make a perfect cut.

Not sure what size your tube is (the below goes up to 35MM) but one of these will cut it in minutes and be perfectly square - why mess about for around $12 ?

 

And another even cheaper that goes to 42mm (I know it's a UK company but there must be comparables stateside
 

Measured the threads today, approx 30mm, what size should I go for ?
I have a washer on top of the progressive spring.





 

I would suggest you measure the inside of the tube and then get as close to that as is available (with it still being able to move freely in case you need to get it out again)

I put Sonic springs in a 1980 Kz750E and they sent plastic pipe. I don’t know the chemical composite. Better check the inside of the upper stantion. Most bottleneck down in size about 2-3in from the top. I’m looking for the drop after I cut them to the correct length. As mentioned a 14” power mitter saw made easy work of getting the pair to correct and exactly the same length. If I find the drop soon I’ll post sizes.

Found the drop. Unfortunately it has the schedule number cut off. The wall thickness is 4.39mm