NEW " Lever Operated Drawbar"

[Scott_M]

Product Announcement

SDM Lever Operated Drawbar with Hydraulic Assist

After a year in development I am proud to announce the release of my new Drawbar for the Tormach PCNC 1100. It is designed to be used with the TTS tooling system.

My typical use of the Tormach is a lot of short cycles with a lot of tool changes. I needed a faster way to change tools. I have no need for a automatic tool changer ( most are to slow ) So I designed a manual Drawbar. I choose manual over air operated for 2 reasons.
1. I did not want my mill dependent on my air compressor.
2. I hate listening to my compressor, it is loud. (5hp 23cfm@150psi)
This offering will be for the complete set of plans to build your own. The package will contain all drawings in PDF, DXF, and .dft ( Solid edge native format ). There is an additional folder with the most likely CNC’d parts laid out a little differently in .dxf format for easy integration into CAM programs. Shop notes and assembly instructions with Bill of materials. All engineering was done in Solid Edge.





This is a good project and a great addition for the Tormach. The motor base casting will need to be modified, this will require access to another milling machine. Tormach carries a few castings in stock they are about $120.00
All parts can be made on the Tormach and a good engine lathe. Good shop skills are a must.

For complete information see here http://www.sdmfabricating.com/LOD.html

This Package has earned the “Tormach Seal of Approval” and will be listed on the Tormach website.

There are several videos in HD format so they may take a moment to load longer on slow connections.
I also spoke with Scott Martinez ( The owner and creator of NCPlot) and got permission to include a trial version of The latest build of NCPlot. If you are not familiar with it you are missing out on a great piece of software. It is a backplotter that gives a graphical view of your code. It is how I learned to write my own code. It is a lot easier to see my mistakes as I type them than at the machine. It also has several cool functions like mirror, rotate, scale and a text to g-code macro.

Depending on the demand I may offer the Uprights as water cut parts. Also, I may offer an exchange program for the modified motor base casting.
Let me know what you guys think
Regards
Scott

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[zephyr9900]

The motor base casting will need to be modified, this will require access to another milling machine. Tormach carries a few in stock they are about $120.00

What's the part number of the $120.00 milling machine, Scott? I can't find it on Tormach's website!

But seriously, that is a seriously nice looking drawbar mechanism. What do you estimate the completed build cost to be?

Randy

[Scott_M]

OK Randy

I knew I could count on you !

added.......... a few"castings" in stock.

I hope that reads a little better.

I would think you could do it for around $500 if you use your own casting. It would depend a lot on what you pay for the steel. And what you have laying around.

Scott

[zephyr9900]

I really like the concept because the only compressor I currently own is a little diaphragm Gast laboratory unit. Is there anything in the design that needs something other than typical mild steel? Any parts need to be heat-treated or case hardened or such? Or is it literally machine up the parts and assemble?

Randy

[Scott_M]

Good question

The lever shaft 1" OD by 9.5"
The rollers 3/4" dia. By .375"
The cam
the cam shaft 1 3/8" OD by 4.5"
the spring cup 1 1/2" OD by 1.55"
the Intensifier 1.3/4" od 2.25"

Should be made from something hard. I used and spec'd 4140 HT for these parts ( about 35 c rockwell )
For the rollers, piston and ram, I used 01 drill rod and hardened them with a torch.

The Belleville springs and the rest of the hardware.......screws ,bearings bolts etc. was about $70.00

[Don Clement]

Looks like a great idea. If I didn't already have the pneumatic draw bar would want one. Does the lever operated drawbar put pressure on the spindle bearings?

Don

[Scott_M]

Hi Don
Yes it does. But the total load is divided by the hydraulics 7:1 ratio so it is only about 300-400 pounds, distributed through all the bearings. And it is a nice gentle loading. You would probably do more harm rapping the drawbar with a hammer to get out a stuck tool.

Scott

[asuratman]

Is this drawbar adaptable to another machine brand like ZYX - 45 that use BT30 or R8?

[Scott_M]

I am sure the concept is adaptable to just about any machine. But the specific parts... I doubt it.

Scott

[philbur]

I don't understand, surely if you are pushing down against the belville washers with 2600 lb then something (in this case the bearings) must be pushing back with the same force.

Phil

Hi Don
Yes it does. But the total load is divided by the hydraulics 7:1 ratio so it is only about 300-400 pounds, distributed through all the bearings. And it is a nice gentle loading. You would probably do more harm rapping the drawbar with a hammer to get out a stuck tool.

Scott

[Scott_M]

Hi Philbur

It's Magic !

Early in my design I had the same doubts but a quick test in the Hydraulic press with a Dillon force gauge proved it out.
The only downward pressure exerted on the top of the spindle is that from the lever. About 300-400 lbs. The rest is trying to push the top off the hydraulic intensifier. The 1 1/2-18 threads keep that from happening. If it was not threaded together the top of the intensifier would just lift away from the spring cup and nothing would move down except the piston. So most of the force is retained in a "Pinch" situation between the spring cup and the intensifier. I guess it really is magic .

Scott

[BlueFin]

I don't understand, surely if you are pushing down against the belville washers with 2600 lb then something (in this case the bearings) must be pushing back with the same force.

Phil

Nice looking product you have there Scott. Philbur, as he said in the video that part of the "goodness" is a secret, but it looks to me like the bellville's might be inside of the hydraulic thing to allow for the pinch effect he is talking about. There must be some kind of oil passages in there to cause forces to occur on both sides of the spring, but by pushing the small piston, I.E. a small volume of fluid per linear travel is pushed into a larger chamber so 300 Lbs downward motion is converted into 3000 lbs of pinching force. But I can only see whats in the same pictures your looking at.

[philbur]

OK know I see how the secret goodness uses the hydraulics to transfer the reaction force to the spindle shaft rather than to the head. It's a very neat and compact solution.

A tidy, no hassle quick tool change is of much more interest than an ATC for me. However it doesn't seem like too big a step to put a motorised worm drive on the lever arm shaft, making it suitable for an ATC, without the noise of a compressor.

Nice one.

Phil

PS: Does the operating lever arm need to be that long.

[Scott_M]

PS: Does the operating lever arm need to be that long.

No, but shortening it will cut down on mechanical advantage. But I think 3-4 inches shorter would be ok.

Scott

[Scott_M]

I have had a few emails about the mods needed for the spindle motor base.
I thought I would post the print so you guys can see what is needed. Basicly we need 6 holes for 3/8 bolts ( marked .386" ) and some of the left side boss removed. ( original boss shown in blue phantom line. )
And a clean up cut will need to be made on the inside bottom of the casting for the uprights to sit on.

Here is the print.




Let me know if you have any other questions.


Scott

[cal50]

Way cool design.
I makes me want to buy a mill and the drawbar assy.

Very nice work.

[Scott_M]

I have had several emails with concerns about heat treating.

I used and spec'ed Pre heat treated stock ( 4140 HT ) it comes at about 35 C Rockwell. If carbide endmills are used it machines beautifully and leaves a great finish. For some of the smaller parts I used 01 because I had it on hand. But the HT stock can be used instead. So no additional heat treating is needed. The levers can be made from mild steel.

I spoke with the shop that did my watercut uprights and he gave me a great price on sets of ten. If there is any interest I should be able to offer a set for around $50.00 plus shipping. This would be for the blanks, they would still need the bores finished and drilled and tapped. The bottom edge should also be cleaned up.

Let me know

Scott

[allennella]

Scott, is there chance that you will be selling the assembly in the future?

I have had several emails with concerns about heat treating.

I used and spec'ed Pre heat treated stock ( 4140 HT ) it comes at about 35 C Rockwell. If carbide endmills are used it machines beautifully and leaves a great finish. For some of the smaller parts I used 01 because I had it on hand. But the HT stock can be used instead. So no additional heat treating is needed. The levers can be made from mild steel.

I spoke with the shop that did my watercut uprights and he gave me a great price on sets of ten. If there is any interest I should be able to offer a set for around $50.00 plus shipping. This would be for the blanks, they would still need the bores finished and drilled and tapped. The bottom edge should also be cleaned up.

Let me know

Scott

[Scott_M]

Probably not. I may offer some of the assemblies , like the Intensifier/Drawbar.

I figured most of you guys would rather build it your self and save a bunch of money. But I guess it is a lot easier to click the buy now button.

Maybe I will start a survey "would you rather buy it or build it" ?




Scott

[Tormachmaster]

How much pressure are those washers compared to just tightening with the wrench? A comparison?