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PM3520B Additional Weight

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Forum topic by Big Ben posted 443 days ago 976 views 0 times favorited 12 replies Add to Favorites Watch
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Big Ben

87 posts in 1515 days


443 days ago

I bought a PM3520B over the weekend. With my previous lathe (Nova 3000) I added weight to the bottom, I am wondering if that is needed for PM3520B. I do want to on occasion outboard large items but mostly do bowls and hollow forms.


12 replies so far

View Kreegan's profile

Kreegan

1452 posts in 772 days


#1 posted 443 days ago

I believe the 3520B is over 800 lbs, so unless you’re planning on turning really large and out of balance pieces, you’re likely good. If it’s an option, bolting it to the floor would still be a good idea.

View Wildwood's profile

Wildwood

987 posts in 760 days


#2 posted 443 days ago

They show a couple different style shelves in the owner’s manual that would let you add weight too. I have one like figure 11 in the manual for my Jet 1642 loaded with concrete blocks. It’s a chip and junk collector. My lathe not bolted to the floor will rock a little with out of balance pieces if speed too high, dialing back speed solves that problem. Your lathe lot heavier than mine, so whether you add weight or not will end up dialing speed back at times.

http://content.powermatic.com/manuals/1352001_man.pdf

Not to worry try it without a shelf for awhile can always add weight later.

Good luck with your new lathe!

-- Bill

View mpax356's profile

mpax356

44 posts in 1117 days


#3 posted 441 days ago

I don’t know any turners that have one who felt the need to add weight. Try it for a while before you bother. I did add a compartment box, but not to add ballast but for some more storage room. It is heavy but certainly not 800#. Ship weight is 682.

-- MPax, Atlanta

View TJinNC's profile

TJinNC

9 posts in 960 days


#4 posted 440 days ago

The physics of adding more weight is always better, especially if you plan on turning out of round or even very large blanks. I put a couple hundred pounds of sand in a tray under my 3520.
Couple other suggestions: Ditch the adjustable feet. If you need it elevated, shim it with hardwood/steel and shim it correctly to be sure you remove as much residual stress in the lathe bed as possible. This will help prevent vibrations caused by poor overall weight distribution to the feet of the lathe.
Do this by lifting up the tailstock side leg from a central position front/back at the extreme right end of the lathe, and notice which support pad becomes ‘loose’ first. Add/remove shims till the feet have equal loading front/back on the tailstock side. The headstock side will be automatically taken care of by doing this properly on the tailstock (lighter) side. Have fun!

View Big Ben's profile

Big Ben

87 posts in 1515 days


#5 posted 440 days ago

TJinNC I plan on getting rid of the levelers and bolting 6×6 post to the legs to get more height to suite me, I am 6’7”.

Does it matter if I have the weight resting on the posts or should it be on the self?

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TJinNC

9 posts in 960 days


#6 posted 439 days ago

Hey Ben…I must be at the other extreme…I’d like to take about 2 inches off my 3520 to make it suit me! :-D
Nothing wrong with applying the weight to the integral supports for a shelf to carry the weight, and the dampening effect of the extra mass will be better if placed on the lathe directly, as opposed to the supports you plan to bolt to. Also, I like having the area clear under the lathe for my feet…and I suspect you’ll need it even more so.
If I understand correct, you’ll have two 6×6 sections to span each leg’s 2 pads, each about 24” or so long. Sounds like a plan. Still be sure to shim out the underside of the 6×6 section on the tailstock end like I talked about above. It will smooth things out and give less chance of ever cracking a bed casting (never heard of it first hand, only word of mouth) due to fatique stress.
6’7”...man, you needed the 4224! Nah, you’re gonna be very happy with the 3520, no better value in a full size lathe out there in my opinion.

View Wildwood's profile

Wildwood

987 posts in 760 days


#7 posted 439 days ago

View PASs's profile

PASs

560 posts in 1724 days


#8 posted 298 days ago

Ben,
I’ve had my 3520 about 18 months.
Even with a 50” and 18” installed I’ve had issues when turning larger (100 lb plus) unbalanced pieces, specially when doing the initial rounding.
I’m still running on the original feet but am thinking about setting anchor/leveling bolts into the garage floor.

-- Pete, "It isn't broken, you just aren't using it right."

View mantwi's profile

mantwi

312 posts in 521 days


#9 posted 298 days ago

The adjustable feet are the weak link in many otherwise robust machines. Picture a 345lb linebacker wearing ballet shoes and running on his toes, he would be a little tippy. The mass needs a good solid point of contact to dampen vibration. Sitting above on four thin bolts isn’t giving it that solid base. As suggested you should either bolt it down or at least use something other than the supplied wimpy adjustable feet with sturdier material.
By the way congratulations on purchasing a great lathe.

View rum's profile

rum

148 posts in 1211 days


#10 posted 297 days ago

I’m in the “more weight is better” camp. I ran my 3520 for about 8-9 months without any and then added a cabinet and put another ~200lbs of gravel into the bottom of the cabinet. Mostly I put the cabinet in because I wanted the storage (and yes it does catch some chips, but not to bad, I made the face of the drawers about flush with the side of the lathe bed and left plenty of room to push shavings out between the lathe bed and the cabinet itself). Anyway with the extra weight there was a noticeable reduction in vibration with even medium sized pieces (kind of like from small shimmer to no shimmer) and larger pieces I could definitely spin up a bit faster.

Did the lathe work just fine for pretty much everything without it? Well yes.. :D but it does imho work even better with it.

View bigblockyeti's profile

bigblockyeti

1468 posts in 346 days


#11 posted 297 days ago

I bolted my little (modified) craftsman to the floor and it made a world of difference.

View PASs's profile

PASs

560 posts in 1724 days


#12 posted 297 days ago

Bigblock,
I had two Craftsman tube-bed lathes before the Powermatic.
Was going to join them end-to-end for longer turning capacity.
Just curious what mod’s you made to yours.

-- Pete, "It isn't broken, you just aren't using it right."

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