Building a beefcake lathe bench

Armorer1984 · Mar 20, 2016

So I have finally started building a new bench for my 9a. The base is a 2" tube steel platform that will become the foundation for the 4" thick concrete top. Here are the steps I have so far.

Step 1. Start a concrete countertop hobby/part time business. While this step is optional (and somewhat discouraged) it does allow you to have the piles of junk around to undertake this sort of thing without having to buy much. Almost everything I am using is scrap I have laying around that is getting in my way. And my wife's. Which is always a bad thing if you value your life at all.

Step 2. Develop a plan to overbuild by a factor of 5. Because, inevitably, you or someone else will have a day where stupidity runs rampant by a factor of 6.

Step 3. Build the form. I am using a near dead flat platform and the concrete is being poured face down. This allows the top surface to be pretty flat no matter how level the form is or how carelessly you throw your form together like I have here. The key to this is making a waterproof basin for the concrete to set in. Moisture lost = strength lost. I am using some 1/8 shower wall panels that have a waterproof surface. Melamine would be the best, but I have this stuff laying around so I used the wall panels instead. Caulk all the joints, make her waterproof.

That's as far as I had gotten today before my back decided to make my left leg go numb. Time for beer and bad life choices. Tomorrow I will set the voids for the lathe foot mounting bolts and the threaded inserts for the drive assembly.

gadget73 · Mar 20, 2016

Those wall panels, are those the fiberglass ones with the texture on one side? If so, I presume you are using the smooth side inwards?

Any special reason for the concrete top, or just use of available materials?

looks like an interesting project. How are you planning to anchor the bed down, lead inserts with bolts threaded in or something else? I've had fairly good results out of those in concrete, though those Red Head ones that look like drywall anchors on steroids work well too if you have enough depth to set them in.

Armorer1984 · Mar 20, 2016

gadget73 said:
Those wall panels, are those the fiberglass ones with the texture on one side? If so, I presume you are using the smooth side inwards?

Any special reason for the concrete top, or just use of available materials?

looks like an interesting project. How are you planning to anchor the bed down, lead inserts with bolts threaded in or something else? I've had fairly good results out of those in concrete, though those Red Head ones that look like drywall anchors on steroids work well too if you have enough depth to set them in.

The panels are a wood fiberboard or sometimes called hardboard. It's the same stuff that pegboard is made of. It just has a sort of plasticy coating on one side that makes it waterproof. It can be picked up for $8/sheet at Menards. Really, any smooth waterproof material would work. For my countertops I usually use laminate countertop material which can be reused dozens of times.

I am using concrete because I want something that doesn't change dimension in a non-uniform way with temperature and humidity changes. Also I am wanting to make my lathe bed more rigid and absorb vibration. So I figured a 27x52 slab of 4" thick high strength concrete would accomplish those things. Plus it is relatively inexpensive. Only $21 worth of portland cement and the gravel and sand only costs $2 at the local gravel pit. Plus a few additives which I will go into later.

The bed will be bolted down with 3/8 bolts through the entire slab, ensuring a stable mount with no movement. The rear drive unit will have 3/8 threaded inserts set into the slab during the pour.

This is overkill in the purest sense and I'm ok with that. Doesn't take much more work to make sure there is absolutely no chance to have structural problems 10 years from now.

Rock6.3 · Mar 20, 2016

I am looking forward to learning how a bench top like this is picked up, flipped over, and placed on the legs.

Concrete is how heavy? 148# per cubic foot?

Armorer1984 · Mar 21, 2016

Rock6.3 said:
I am looking forward to learning how a bench top like this is picked up, flipped over, and placed on the legs.

Concrete is how heavy? 148# per cubic foot?

You are correct. My spreadsheet calculates just shy of 500 lbs.

The way I usually flip em is to use an engine hoist and lift each end, sliding a 2x4 under each end and then screwing another 2x4 on top, making a sandwich. A block is screwed down beside the slab to act as a tipping point. Then with a big burly guy on each end we tip the slabs on end using the 2x4's as levers. The slabs are then tipped over onto a polishing table that is the same height as the pouring table. A nice gantry crane would be handy, but this gets the job done on the cheap until my hired help refuses to be paid in beer.

Armorer1984 · Mar 21, 2016

So tonight I have had a change in plans. Originally I had planned on mounting the lathe feet to the slab by casting the slab with through holes and by using a bolt and nut on each foot. Thinking about how many profanities I uttered the last time I had to cast deep voids, I opted to make threaded inserts that will be cast into the concrete.

Made them using some 3/4 cold roll and tapped them 3/8-16. Total length is around 3".

As a side note to those of you wanting to do this, remember that when you cast upside down, everything is reversed (mirrored). I just realized my pins are on the wrong side. Time to call it a night, I think.

hanermo · Mar 21, 2016

Fwiw..
A long time ago, about 2004, I bought a 7x minilathe (yes, I know).

I then built a similar rigid concrete bed for it, rigid mounted into a steel frame.
My frame is 120x12 mm mild steel, is 120 mm thick, or 5", about 65x90 cm.
Preloaded via rebar crossed inside, and under heavy tension.
Rebar was welded inside the box, and the 3x15 mm pieces welded to each other.

Bed is 150 kg in mass (lathe is 40 kg).

Havent used the toy lathe for years, but..

The lathe became about 4x more rigid, and the noise dropped by a lot, since the frequency is much lower.
Technically, the project was a great success.

Took about 250€ in materials, and 200 hours of work.
With paint, laquer, rods, rebar, granite plate underneath so it does not stain, rubber feet at bottom (150 kg rated anti-vibration feet).
All the extra little bits and pieces added up.

Practically, for me, was a waste of time and money, I should have bought a bigger lathe.
I then did, an industrial-type 12x.

As a learning experience, it was very worthwhile.
Also, was first "machine tool" piece I ever built, and worked extremely well.

Moral of story.
It will probably work well.

mdshunk · Mar 21, 2016

When I see the very nice (but massive) lathe benches guys build, I can't help but to remember old South Bend factory photographs. They have what appears to be rooms full of 9" lathes on legs on a second floor of a wooden floor factory churning out parts. They seemed to be stable enough for South Bend.

MilGunsmith · Mar 21, 2016

During WW2 there was a publication on building concrete lathe benches to help make them run more accurately. This was to help with the war effort.

moonlight machine · Mar 21, 2016

I see this and it just confirms what I have thought for years....SB guys are NUTS. That bench will weigh more than the flimsy little lathe you are putting on it. BTW why didn't you fill the corners of your mold so the benchtop does not have sharp corners?

mdshunk · Mar 21, 2016

moonlight machine said:
I see this and it just confirms what I have thought for years....SB guys are NUTS.

Can I tell you a meatball sub story? My father once owned an ice cream shop and he wanted to serve sandwiches and soup at one point. His favorite sandwich was a meatball sub, so he started by only offering meatball subs. He thought everyone in the world loved meatball subs too. Nobody bought them. Some people only really wanted a ham and cheese.

jim rozen · Mar 21, 2016

Is the thermal expansion of concrete similar to that of cast iron?

If not consider allowing the right hand (tailstock side) bed support to float in the direction along the bed.

SteveM · Mar 21, 2016

Armorer1984 said:
As a side note to those of you wanting to do this, remember that when you cast upside down, everything is reversed (mirrored). I just realized my pins are on the wrong side. Time to call it a night, I think.

Wouldn't you want the flange on the pins to be on the underside? That would prevent the pins from getting pulled out.

You could weld a cross-pin on the side (or thread a nut onto the outside) to prevent pull-out.

Steve

moonlight machine · Mar 21, 2016

mdshunk said:
Can I tell you a meatball sub story? My father once owned an ice cream shop and he wanted to serve sandwiches and soup at one point. His favorite sandwich was a meatball sub, so he started by only offering meatball subs. He thought everyone in the world loved meatball subs too. Nobody bought them. Some people only really wanted a ham and cheese.

And just what does this have to do with the price of tea in china?

stephen thomas · Mar 21, 2016

If not consider allowing the right hand (tailstock side) bed support to float in the direction along the bed.

My SB 10K has that feature built into the TS end pedestal. Floats lengthwise, and can be adjusted for twist with an allen ss on either side. Thought it was usual?

OP- wife want concrete counters eventually, so I am enjoying the tutorial. Keep it coming, thanks!

smt

Fabworks · Mar 21, 2016

Check out this hardware for your embedded anchors. Back in the day we used these all the time. Screw the plastic insert into the form on layout, then screw the ferrule loop anchor onto the insert.

https://www.patterson-online.com/content/customer/docs/pdf/ALP_FERRULE_INSERTS_092012.pdf

Armorer1984 · Mar 21, 2016

moonlight machine said:
I see this and it just confirms what I have thought for years....SB guys are NUTS. That bench will weigh more than the flimsy little lathe you are putting on it. BTW why didn't you fill the corners of your mold so the benchtop does not have sharp corners?

I agree I am nuts, but the lathe doesn't have anything to do with it. FWIW, I hardly consider this machine flimsy. It's built well, makes consistent parts, and is the perfect size for my needs. It just needs a bench that doesn't warp and swell with the seasons. Its like saying the Ferrari is worthless because it has a left rear tire that slips a belt and causes the car to drive weird every so often. You don't call the car flimsy, you get a new set of tires and keep smiling.

I did fillet the corners of the mold with silicone,but it's white which makes it awfully hard to see.

Armorer1984 · Mar 21, 2016

jim rozen said:
Is the thermal expansion of concrete similar to that of cast iron?

If not consider allowing the right hand (tailstock side) bed support to float in the direction along the bed.

It's pretty darn close. Cast iron has an expansion coefficient of 6 millionths in/in and concrete has an expansion coefficient of 8 millionths in/in. I think the difference with be minimal over the 36" between the feet.

hanermo · Mar 21, 2016

Yes.
Thats why rebar works in concrete.

jim rozen said:
Is the thermal expansion of concrete similar to that of cast iron?

If not consider allowing the right hand (tailstock side) bed support to float in the direction along the bed.

jim rozen · Mar 21, 2016

hanermo said:
Yes.
Thats why rebar works in concrete.

Rebar has a different thermal expansion number than cast iron. Cast iron is larger.

"my SB 10K has that feature built into the TS end pedestal. Floats lengthwise, and can be adjusted for twist with an allen ss on either side. Thought it was usual?"

After a certain time. Most 9" machines are not done this way, they are designed for bench mounting and the feet on the TS side are designed
to bolt down and be allowed to slide under the bolts If the TCE numbers quoted are good it won't be a big issue. But I'd still bolt the
headstock end down snug and put something that would give some slide under the TS side foot, like a piece of thin phenolic or something.
And not crank down the bolts real tight.

Building a beefcake lathe bench

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