billie5150,if the model in your post is a Singer 251- 1,( I can't tell by just looking at it ),it only has a 9/32 inch presser bar lift.A bit more than a 1/4 inch,I think.Not enough to get real thick,double folded jeans side seams under the presser foot when shortening jeans,without hammering the seam down first and using a hump jumper
Depending on how thick the canvas and other materials are you are thinking of sewing,I would think real hard before I would buy that model.Here
is a free Singer 251 pdf manual.If you like to,you can read all the good things about that model.( I have seen another ad with a better looking 251 for two hundred dollars.)
In the manual it also says.....Machine 251 - 2 has a needle bar stroke of 1-13/64 inches and a presser bar lift of 5/16 inch;can sew a maximum of 5 - 1/2 stitches to the inch on heavy to to light weight fabrics.
There is also a Singer 251 - 3.The 251 - 3 can be furnished with a presser bar lift of 7/16 inch,enabling it to sew extra - heavy to light weight material.If I wanted to sew a lot of heavy weight material,I would only buy a machine that has at least a 1/2 inch or more presser bar lift.
Some domestic sewing machine brands and models can be used for occasional
heavy weight materials and thin leather.I have sewn teepees for DH.One with an older model Kenmore domestic sewing machine.It had a 1 amp motor.Another,much larger and taller,teepee I decided to sew with my Pfaff 262 - 261 domestic sewing machine because of the speed.It has a 1.2 amp motor and can sew 1500 stitches per minutes with the original motor.
All my Pfaff domestic machines have very good needle penetration.With my Pfaff 1200 series machines I can sew one single stitch at a time - without ever touching the balance/hand wheel.That took some getting used to for me.
The Pfaff dealer,who sold me the machine,pretended to slap my hand when I started to sew and wanted to turn the hand wheel first.I had to do that with all my other brand vintage machines.
The teepees didn't have very thick seams.I could get the canvas material under the presser foot without pushing or pulling.The feed dogs transported the material on its own.My 262 has only a 7 mm,(a bit more than 1/4 inch),presser bar lift.I have sewn thin leather and a few other outdoor things on it for DH,but ...I don't like to sew over bulky jeans side seams with that machine.