Arkk's Weight Lifting / Fitness Thread

Tuco said:

I've heard the same horror stories of 45lbs weighing in at 38lbs and when I bought the cheapest weight set you can buy and was surprised when I weighed it, it had no error that was perceptible by my digital scale (0.1lbs precision, unknown offset, but it nailed all the weights).

Good luck with your project, but unless you've already spent a lot of time lifting before you might want to consider buying a budget barbell and a minimal set of plates before going through the effort of machining them. Keep us up to date!

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Cathan said:

/enginerd on

My cousin has a machine shop and he's been a professional machinist for about 50 years, even used to teach at the local community college. I'm an engineer so I googled up the dimensions of all the plate sizes. 45s have a std diameter of 17.5" but the thickness and other cutouts all vary by manufacturer, except inner diameter onto the barbell sleeve for olympic barbells is 2" (50.8mm) and the barbell sleeves are 50mm (1.97"). 35s and lower you can't even find a standard for outer diameter so I just ran an average and rounded to a diameter I felt comfortable with. The weight of steel from college memory and google is 490lb/cubic foot, exchange that to pounds per square inch and calculate the volume of the plates based on outer/inner diameters and some cutout grooves.

My goal is to purchase steel stock in 18" diameter and other diameters from a distributor that stocks and plasma cuts steel if it's reasonably priced. I wasn't at all thinking to weld random pieces of steel or melt anything down. I can weld but the time and cost would be exorbitant plus it would look like shit and not be balanced on the bar. I don't know anyone that has equipment to cast steel. As an engineer - making quality steel is a very, very precise process to nail the correct heat, non-iron very small amounts of chemicals and ensure they are well mixed and cooled plus formwork. Purchasing steel is the only way to approach this imo. It'd be cool to see someone weld their own plates and nail the weight.

Another reason I wanted to machine my own plates is there's a 3-4% variance in weight for any cast iron plate from almost any company you buy. I read a shitload of articles about 45 lb plates weighing as little as 38 lbs and as much as 59 lbs. As an engineer with knowledge how to create plates and a facility to do it - why not machine my own plates that have less variance in weight than Rogue's TOP of the line machined plates that might cost me a $1/pound finished cost with my own labor? Rogue won't even hit the weight exactly as close as I will. WITH finished paint I want 1, maybe 2 ounce, variance. Anything more than that and I'll be welding steel on or machining down the groove more.

The 45s I designed are only 3/4" thick with about a 2" groove on each side near the outer diameter of the plate. I didn't design them thicker for 2 reasons: 1) the more steel I cut out of the plates to make them deeper dished the more steel I waste, 2) my cousin will be pissed if I burn up all his tools that cut steel off the plates.

I don't care about 35s so I designed 25s and 10s also. I'll just buy 5s and 2 1/2s unless we have extra steel.

My cousin (2nd cousin) is in his 70s so he understood I don't want to pay $3 per pound (I can't find any plates in stock at rogue or any company to order right now) and all the plates I see on fb or craigslist etc are minimum $2/pound. The more important reason I wanted to make my own plates

Here's the calcs I ran to create these. I was going to buy a bar and take it to the machine shop with me to nail the inner diameter fit and get the process/weight down precisely.

45 lb Plate measurements
steel = 490 lb/cu ft = 0.283564815 lb/cu inch 1" = 25.4 mm

diameter 450 mm 17.5 inches

inner hole diameter 50.8 mm 2 inches the barbell sleeve will be slightly smaller in diameter

T45 = 0.75 inch

Volume of a steel plate = (Pi()*(d/2)^2-Pi()*(di/2)^2)*T-(Pi()*(16.5/2)^2-pi()*(15/2)^2)*.5 159.4849146 cubic inches
18" outer diameter, 2" inner diameter, 1.5"wide groove near outer plate on both sides 1/4" deep
Weight = Cubic inches * lb/cu inch 45.22431026 lbs (machine down from here)
likely a 1 1/2" wide groove from 16.5" outer diameter to 15" inner diameter
Start with 18" diameter steel stock
2.0" (50.8mm) diameter hole in the center, test fit of actual olympic bar to verify fit is snug enough, 50mm bar sleeve inside 50.8mm plates
Check the weight, the goal is never to cut the plate below 45 lbs
Machine down the outer diameter to 17 1/2"
Check Weight
Machine out 1.5" groove 1/4" deep on both sides checking the weight at a 1" groove, 1.25" groove and edging toward 1.5" or > as necessary

25 lb plate measurements
diameter = 11 inches
T25 = 1.125 inches
Volume of a steel plate = (Pi()*(d/2)^2-Pi()*(di/2)^2)*T-(Pi()*(10/2)^2-pi()*(8/2)^2)*.5
89.24086632 cubic inches
11" outer diameter, 2" inner diameter, 1.5" wide groove near outer plate on both sides 1/4" deep with outer diameter of 10"
Weight = Cubic inches * lb/cu inch 25.30556973 lbs (machine down from here, probably 2" diameter or > groove)
likely a 2" wide groove from 10" outer diameter to 8" inner diameter
10 lb plate measurements
diameter = 9 inches
T10 = 0.75 inches
Volume of a steel plate = (Pi()*(d/2)^2-Pi()*(di/2)^2)*T-(Pi()*(7.5/2)^2-pi()*(6/2)^2)*.5
35.93196598 cubic inches
9" outer diameter, 2" inner diameter, 1.5"wide groove near outer plate on both sides 1/4" deep
Weight = Cubic inches * lb/cu inch 10.18904128 lbs (machine down from here)
likely a 2" wide groove from 8.5" outer diameter to 6.5" inner diameter


York
Weight 2½ Lb 5 Lb 10 Lb 25 Lb 35 Lb 45 Lb
Diameter 5 ⅝” 6 ½” 7 ⅜” 11 ⅜” 14 ⅛” 17 ½”
Thickness ½” ¾” 1” 1 ¾” 1 ½” 1 ½”

Rogue
Weight 2.5LB 5LB 10LB 25LB 35LB 45LB
Diameter 6.3" 7.75" 8.9" 10.9" 14.0" 17.5"
Thickness 0.5" 0.6" 0.9" 1.4" 1.3" 1.3"

Fringe sport
Weight: 2.5LB 5LB 10LB 25LB 35LB 45LB
Full Diameter: 6.5 7.75 9.5 11 13.75 17.5

My plate diameters 7.5 9.0 11 17.5 I drew this shit up on autocad too (downloaded it free from work onto my work laptop but I don't have layers to draw dotted lines correctly so I drew these up by hand and mailed off my calcs/ hand drawings to my cousin)

/enginerd off

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McQueen said:

My gym closed abruptly. The next best gym is farther away and $65/month. Then the Canton Coof hit. Living under quarantimes has made me realize a home gym setup is probably best. The 5/10/15/25/35 dumbells and bowflex adjustable bench I have for emergencies is inadequate. The bench, particularly is fucking garbage.

It’s all sold out now, but I’m looking at an entirely Rogue setup because it’s what I know.

I’m looking at a monster lite squat stand, adjustable bench 2.0, ohio bar, 260 lb bumper set, rowing machine, and sled as a starting point..... assuming I find it in stock.

Open to suggestions.

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Foler said:

Fucking miss the gym. I don't even cardio outside, especially in Florida summer. Well now that may change...

It's been impossible to find workout equipment. Dumbbells are as hard to find as n95 masks. Was thinking of ordering a peleton bike but now they're saying something like 8 week delivery. Thought to myself, nah, not worth the money, gyms will be open by then maybe.

Now thinking maybe they won't heh.

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