MK 5/V Headstock ?

[judaspre1982]

Right now I have 3 operational MK 5/V headstocks. The 3 headstocks have all new belts installed and adjusted properly. Components are freshly lubed. The first is a 1955 model that is converted to a Poly V drive system. The motor bearings are original. The second is another 1955 model that has the Gilmer drive system with new idler shaft/bearings. All other components(except belts) are original from 1955. The third is a 1995 model, Poly V drive system and is also original (except belts). My ? is how long does it take your headstock to wind to a complete stop, from the low setting, after turning it off? I compared all 3 headstocks and it seems the two Poly V systems take almost 2seconds to stop while the Gilmer drive unit takes over 5sec to stop. The unit converted to the Poly V drive always came to a stop quicker then the Gilmer drive unit, even when both 1955 units were completely original. Just trying to get some feed back on others experiences with different headstocks and what seems "Normal" for the time it takes the headstock to stop on low setting and no attachments or SPT on the machine. Thanks---Dave

[JPG40504]

Right now I have 3 operational MK 5/V headstocks. The 3 headstocks have all new belts installed and adjusted properly. Components are freshly lubed. The first is a 1955 model that is converted to a Poly V drive system. The motor bearings are original. The second is another 1955 model that has the Gilmer drive system with new idler shaft/bearings. All other components(except belts) are original from 1955. The third is a 1995 model, Poly V drive system and is also original (except belts). My ? is how long does it take your headstock to wind to a complete stop, from the low setting, after turning it off? I compared all 3 headstocks and it seems the two Poly V systems take almost 2seconds to stop while the Gilmer drive unit takes over 5sec to stop. The unit converted to the Poly V drive always came to a stop quicker then the Gilmer drive unit, even when both 1955 units were completely original. Just trying to get some feed back on others experiences with different headstocks and what seems "Normal" for the time it takes the headstock to stop on low setting and no attachments or SPT on the machine. Thanks---Dave

How easy does the spindle shaft turn by hand when in 'low speed' setting. Turn easy = long time to stop. With the motor belt removed(from motor pulley) how long does the motor by itself take to stop.

When power is cut off, the inertia in the motor is the force input to the 'system'(and the inertia of the spinning pulleys), and the frictional losses of the bearings and belts are resisting continuation of motion. Shaft/bearing wear, belt alignment, lubrication all affect the slow down force. The mass of the motor armature will determine it's available force to overcome those losses.

Methinks you are worrying about something with many variables not under your control, or that which would require more time to determine than it is worth.

This is a catch 22. Long stop time indicates less frictional losses etc., but long coast down times can be a detriment to productivity if you are often waiting for it to stop. Think about the newer drills which brake when turned off.

P.S. ever use an older electric drill with ball bearings?

[mikelst]

Do you have the same 'load' on all the systems? A heavy saw blade or disc sander would add a 'flywheel' effect would spin down slower than an empty quill.

Mike

[judaspre1982]

JPG, a very in formative answer. I notice the 1955 unit with the Gilmer drive is easier to turn by hand from the drive shaft hub than the other two units. I get the same results with the drive belts disconnected with regard to stop time , only it is a longer stop interval. The 1955 unit with the Poly V upgrade has a GE motor, while the other 1955 and the 1995 have AO Smith motors. I am not troubled by the differences in stop time, I am just curious as to why the differences and what others are experiencing. Again great info JPG---Thanks---Dave

[judaspre1982]

Mike, all tests I conducted were with no accessories or SPTs connected.-----Dave