Low drawbar pressure, what do I do?

[bob1112]

We just had our draw bar tested at 120lbs!!! can anyone tell me is this means my washers are toast or what? Also, how do I get the draw bar out, is there adjustment for it, and do I have to pull the spindle just to get the draw bar out?

[rlabonte18]

Sounds like your washers are bad/broken. There is no adjustment for the clamping force which is regulated by the washers. You will need to pull the spindle cartridge out and depending on which type of spindle you have (direct drive or belt drive) one has a snap ring on the top and the other has screw in pins on the side that have to be removed. If you have a good reputation with your hfo you can buy just the drawbar otherwise they will try and sell you a whole spindle cartridge. The washers can be matched up with some from Mcmaster carr or MSC. I think there are 108 washers in a vf2 not sure what you have.

[bob1112]

Yeah, we have the draw bar in hand and I pulled it out the top and it was NOT fun. I think dropping the spindle would be much easier. Had to move the motor up top to get room. Over half the washers are shattered. I have the washer specs and count but no idea how they stacked them because they are broke. I am trying to figure that part out. I will check McMaster though. Good call.

[rlabonte18]

We have a new drawbar on hand I can check the orientation of the washers Friday. It is for a VF.

[bob1112]

That would be great. I will order washers tomorrow so it will probably get assembled Sat at the earliest. Thanks!

[Geof]

As a matter of interest how old is this machine and how many tool changes has it done?

[bob1112]

The machine is am 97 and has 750K tool changes roughly.

[Geof]

Originally Posted by viper6383 The machine is am 97 and has 750K tool changes roughly.

750K!!!!!!!

That is a relief; I think my oldest and heaviest used machine has about 250K, maybe less, so I don't need to worry for a lot of years.

[bob1112]

I would sure not rely on the number of tool changes to assess the condition of the draw bar. This machine is only 10HP and mostly runs small cutters. If I stuck a big cutter it, it would probably drop a tool and kill the spindle. We are now ordering a force gauge because 1K investment now can save a huge headache later.


Other things affect the DB life like type of material cut, size of cutter, HP of machine (which will relate to force on a cutter), weight of tool, length, etc. My bar was considered FUBARED or totally jacked. It has already cost me about 400 in cutters before I decided to look into the problem.

[Geof]

Originally Posted by viper6383 I would sure not rely on the number of tool changes to assess the condition of the draw bar...

No, I didn't intend to suggest that is what I would do. What I meant was that if any machine gets up to 500k in tool changes I should consider pulling things apart and replacing all the Bellevilles before getting problems.

[rlabonte18]

here are some pics. There are not as many washers as I thought must have confused it with another machine.

[rlabonte18]

If you can see it the first washer by the collet is by itself and the rest go in pairs of 2 also notice the spacers a few washers in on the motor side.