Vacuum Adapter for Your Lathe

Need another option for reverse turning?  A vacuum chuck could be your answer.  

Yes, there are other methods of reverse turning, but vacuum chucking allows you to hold natural edge pieces with ease.  The objects that can be held by vacuum chucking are endless and the best part is that its easily modified!

The following will spare you the learning curve I had and hopefully get you on your way quickly.  My lathe has a hollow spindle with a few cross-drilled holes.  This forced me to use a through spindle vacuum adapter instead of something like the Oneway Rotary Adapter.

If you are like me, youve spent a great deal of time studying online articles learning how to accomplish the task at hand.  Many designs rely on using a double sealed ball bearing as a component to be a vacuum seal.  I was skeptical of this, but moved forward in spite of my doubts.

For this system, you will need to buy or make an adapter for each side of your lathe.  One will fit on the outboard side and the other will match the morse taper of your spindle.  You will need two ball bearings.  I used a R10 and 6000 series bearings.  I would recommend double sealed bearings simply because of the dust that will be present .  The main aspect that drives bearing selection for this purpose is the size of pipe fittings you will use.  I had the R10 bearing on hand, so I had to use a 3/8 NPT fitting to adapt to this bearing. 

In addition to bearings, you will need:

• material for your spindle adapters
• an assortment of pipe fittings
• all thread lamp tube (3/8" OD, 1/8-27 thread)
• valve rated for vacuum
• vacuum pump (well geez, I wouldnt have thought of that)
• filter for your pump
• vacuum gauge
• tubing (size of pipe fittings)
• pipe tape/pipe dope
• epoxy
• a bleeder valve is nice but not a must have
• a muffler for the vacuum pump
• electrical switch
• wire nut
• pliers and wire strippers
• wranches (wrenches for those of you not from the south)
• someone else to do all the work for you! (optional)

So, once youve assembled all of your loot, it may look something like this.

I started off by making the spindle adapter for the outboard side of my lathe.  I used Delrin for this piece because it is not porous, can be shaped by hand with wood turning chisels, and it was available.  Good reasons, I think.  The downside to Delrin is that its terribly difficult to permanently bond something to it.

The criteria for this part are as follows:

• needs to fit onto lathe spindle without too much slop
• hold bearing with slip/press fit
• allows lamp rod to pass through it and clamp on an internal step

This sketch describes how this part works in the original design.

Here are the process photos of making the outboard side spindle adapter.

Rough turning spindle adapter

Ball bearing recess

Flip it!

O.D. profiling

Sized to fit out board spindle

Finished bearing side of adapter

Now, lets move on to the inboard spindle adapter.  For this item you need to:

• match taper of spindle
• allow lamp rod to pass through 
• make a surface for nut and washer to lock lamp rod in place 

Here are the process photos of making the inboard side spindle adapter.

Roughing inboard adapter

Turning recess

Test fit

Reducing O.D. of  adapter

You may have noticed that I switched lathes while making this piece.  I did this because my Nova G3 chuck doesnt have a large enough opening that I could push the spindle adapter into.  Using the Vicmarc 120, I was able to hold the spindle adapter on the larger diameter and form a recess for the washer and nut to sit in.

Well, the spindle adapter is wrapped up... for now.

The next thing to move on to is pipe fitting!  Oh what fun!  I wanted to use push to connect (PTC) style fittings for this system so that I could easily adapt the vacuum pump to be used for other applications in the shop.  While PTC fittings are not the answer for this application, this blog is a journey and youre invested, so lets see how things go.

Turning threads off fitting

Bearing, fitting, epoxy...

I didnt get epoxy on myself!

Remaining parts for system

Manifold components

Now with those parts all married, lets plug the suction end of the system and see what the vacuum gauge reads.  This is where my disappointment began.  For the pump to pull down more than 5" Hg, I had to push and hold the tubing into the PTC fittings...  That will be hard to do while Im turning.  In addition, the double sealed ball bearing was another leak.  In an effort to remove as many potential leaks as possible, I rethought the design of my spindle adapter and replaced the PTC fittings with compression fittings.

I started by removing the plastic PTC fitting I had all too recently epoxied into the ball bearing.  But first I needed to remove the ball bearing from the outboard spindle adapter.  This was easily done by putting a screw driver inside the fitting (through the bearing) and hitting it with a hammer (plastic, no one wants a cracked screw driver) a few times.  I then scuffed up the inner race of the bearing for the next fitting to be epoxied.

To remove the need for the seals of the ball bearing to hold vacuum, I changed the plumbing and affixed the lamp rod to the ball bearing with marine grade epoxy.  This involved a few extra steps, which are shown with pictures below.

Remove threads: 3/8 fitting

Cut off one side of 1/4 NPT

Tap 1/4 NPT with 1/8-27 tap

All parts epoxied together

Now that Ive affixed the lamp rod and bearing, I need a ball bearing for the other spindle adapter.  By assembling the parts in this manner, I no longer need the "step" in the outboard spindle adapter.  However, there is no need to remove it or remake the part.

Size adapter to fit bearing

Replacement compression fittings

Testing new configuration

The last step is to attach the tubing from the pump to manifold and from the manifold to the spindle adapter.

Tube fitting for spindle adapter

Vacuum system!

Zip tie capacitor to keep it tidy

I recommend testing your system for leaks before you use it for turning.  A good way to do this is to plug or otherwise seal the open end of lamp rod, let the system pump down as far as it will go, and then valve off or turn off your pump to see what the leak rate is.  This system isnt for a particle accelerator, so no need to go overboard.  However, if the vacuum drops rapidly, you may want to look into it.  A good way to find leaks is to mix up some soapy water and apply it to each of the connection points.  You will see bubbles wherever there is a leak.  Just give the fitting a bit more oomph and retest.

I will soon post about building vacuum chucks.  I will be making my chucks completely from materials I have on hand and those commonly found at a big box hardware store!  No face plate required for the method I will use.  Once the holiday season is past, or once I catch up on my ornament orders (which ever is first), Ill make the vacuum chuck and finish off a platter!

Thanks for reading!  As always, if you have any questions or comments, dont hesitate to contact me.

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A New Heart for Big Blue

While turning some 20" platters, I came to the realization that my beloved lathe needs a new heart. Not just any heart, a bigger, stronger, slower heart.  Slower?

Yes, a new motor was in order for my lathe.  The 2hp is good, but when turning large pieces at low speed, it lacks the torque needed.  So, here is where the dilemma begins.  My first thought was to get a 3 or 5hp motor with the same nameplate speed as my current/previous motor.  But, then I have to replace the VFD (brain) with a unit that can handle the increased amperage of the bigger motor.  AHHHHH!!!

Good thing I had more than one thought.  Not initially realizing that motors come in many different RPM ranges, I proposed my situation to my local surplus dealer.  He pointed to a LARGE 2hp motor that is a 870 RPM model.  While he didnt say it, I know he was thinking "Thats the one I tried to give you before."  DOH!!  

So why would I replace my existing 2hp motor with another 2hp motor?  The reason is due to the speed rating of each motor.  The original is rated at 1700 RPM, while the new one is a 870 RPM unit.  The hp rating of a motor is a result of RPM and amperage.  This means that the new motor (870 RPM) has twice the torque of other unit!  In addition to more torque, Im still retaining similar spindle speeds on the lathe by putting a larger pulley on the new motor.  If you cant tell, Im excited!  Below are the two motors side by side.  They seem to be playing nicely.

Well, thats the why.  Heres the how.

This motor came with a key already in the arbor.  I thought this was excellent until I had to remove it to accommodate the bushing and pulley style I used.  So, here is a quick tip in removing a stuck key.  DONT GET A BIGGER HAMMER!!!  I used a small plastic face hammer with a tiny screwdriver to try and pop the key out.  After not having instant success, I grabbed the penetrating oil.  I sprayed down the key and let it soak for a day.  The next morning I tried again without success.  Now I grabbed a pair of vice grips and a propane torch.  After applying heat for maybe a minute I grabbed the key with the vice grips and rapidly tapped the vice grips with the plastic faced hammer.  This lifted up the end of the key allowing me to use a small screw driver to pry the key out with little force.

Now on to attaching the pulley.  I bought a keyed H-bushing and pulley from surpluscenter.com, mainly because it was affordable and fit my needs.  

Having not used this type of pulley before, I did the stupidest thing possible when I initially tried to marry the pulley to the motor.  I fully seated the bushing into the pulley and then fruitlessly tried to push the pulley onto the arbor.  It wasnt until this that I realized a H-bushing and pulley is tapered and not intended to be assembled in this manner.  Luckily, I was able to separate the bushing and pulley using the jack screw holes on the bushing.  

This time, I slid the pulley onto the arbor with the tapped holes facing away from the motor.  Next, I slid the bushing in snug to the pulley and pushed the key into place.  Now I used the provided screws to pull the bushing into the pulley until tight.  I didnt use a torque wrench, I just tightened until it seemed reasonable for the bolts provided.  

Its amazing how easily things work when you do it right...

Now to heave this beast onto the lathe.  Mind you, the "small" motor was 79 pounds.  The new motor is 120 pounds.  Thats heavy when you have to hold it 5 inches off the ground and hang it on a few bolts.  No, I dont have a hoist or anything that would have made this an easy task.  What fun!

Well, other than trowing some new belts on, this upgrade is wrapped up unless you want to hear about wiring...  Ok, ok, Ill tell you about wiring the motor.  Before I took the original motor off, I tested the new motor.  It is surplus after all, and wouldnt I have been ill if Id gone through all that work just to put the original motor back on.  So, basically you follow the diagram on the motor for wiring.  Use wire nuts and make sure you ground the thing.  Ok, done!  The heart transplant was a success!

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Who Won the Ornament Giveaway

Congratulations to Marie, the winner of the ornament giveaway!  

Thank you to all who entered!  If you just had to have one of these you know who to Email.

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Lathe Cart

Here is the tool cart I built for all things wood turning.  

You know the scene...  Tool pandemonium.  You set out to use your lathe, but first you have to round up all the necessary equipment.  Let me get my face shield, my dust mask, earplugs, tool wrap, chuck, faceplate, and the list goes on.  Next I need to clear off a work bench or cart to put all of these items on. After the time youve spent just getting ready to mount your piece on the lathe, its lunch time, or you get a call and you have to stop what youre doing. A lone tear drips from your eye...  To add to the insanity, since all of your tools are strewn across a bench top, its real work to find what you need.

I got tired of this in a hurry and set out to design and build a rolling cart that would fill the need.  I started by identifying what exactly I wanted out of such an assistant.  Well, first and foremost, it needed to hold tools.  Also, of utmost importance, is a surface large enough to hold a bench grinder.  The only thing better than having someone sharpen your tools for you is having the grinder close by while you are working.  I also wanted space to store essentials like chucks, extra jaws & associated hardware, faceplates, sand paper, air tools, project supplies and other miscellaneous items.

The top surface that my grinder is mounted to is about 44" from the floor. The case dimensions are 30" wide and 20.5" deep.  I have casters on this cart also, so that I can position it for either lathe that Im working at.

I built the case and drawer boxes from 3/4" cabinet grade plywood with 1/4" luan for the drawer bottoms and the cases back.  I used pocket drilling to assemble the majority of the case and drawer boxes.  No, I didnt buy the Kreg jig...I made one.  Maybe Ill explain that in a future post.  

I bought 18" full extension drawer slides off Ebay.  I also bought in bulk since Im planning to add some drawers to my workbench.  The handles and casters I picked up at local hardware stores.  

Helpful Hint:  While doing projects like this, dont forget to check out the clearance and bargain bins. I was lucky and found just enough handles on clearance for this project.  

You can probably recreate the dimensions for this project without too much trouble.  However, if youd like, I do have CAD models available for a small fee to take out the dimensional guesswork.  Just send a message if I dont have the CAD uploaded yet.  Just to let you know, this model is intended to be a guide and is not a fully detailed.  If you require such drawings let me know and Ill accommodate your request.

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