trouble sawing 7inch solid aluminum

[timmydabull]

i just recently purchased a used hyd mech 20 inch saw,i have refurbished everything like new except replaced the hydraulic downfeed system,the problem is i have been thru 5 blades of various types and teeth count and i cant get this saw to give me good results. and hyd mech has let me down big time wasted 2 weeks of my time and dont seem to have any level of quality support or service for this saw.

as of now it takes 35-60 minutes to saw thru a 7 inch round solid 6061 bar and if i dont stand over the saw and constantly adjust the flow control valve the saw will stop decending or decend too fast and break teeth off the blade.

i have never used a saw like this so i do not know what the normal cutting time or feed speed and blade configuration for optimal cutting.

one part of me says to replace the hydraulic cylinder but the other part of me is frustrated and ready to spend money i dont have on a new saw.

this saw has put me in a bind because i cant get material into the machine because i cant cut it,and there seems to not be anyone to call locally who can help.

can anyone provide some insight as to what i may be doing wrong and what i should try.

thank you

[Andre' B]

if i dont stand over the saw and constantly adjust the flow control valve the saw will stop decending or decend too fast

Possible that there is some crude floating around in the oil, plugging up the valve, you then open the valve some and let the bit go thru.

You could try flushing the system out and putting clean oil back in.

[timmydabull]

i dissasembled the hydraulic cylinder flushed everything out with mineral spirits and then reassembled it with a new flow control valve.

it is possible that may be it but i have cleaned it the best i can. ps i used light hydraulic fluid to replace the oil in the cylinder.

thank you for the suggestion.

[masonbcaldwell4]

I know that the usual speed for 6061 is around 200-230 fpm, and while this should have nothing to do with your downfeed rate, it might save a blade or 2....

[Geof]

Originally Posted by timmydabull ......ps i used light hydraulic fluid to replace the oil in the cylinder.......

If the cylinder did have just regular lube oil in it and you replaced it with proper hydraulic fluid this could be the problem. Some seal material that is resistant to lube oil is not resistant to hydraulic fluid, and vice versa.

[timmydabull]

what type of fluid would you reccomend?

thank you

[timmydabull]

Originally Posted by masonbcaldwell4 I know that the usual speed for 6061 is around 200-230 fpm, and while this should have nothing to do with your downfeed rate, it might save a blade or 2....

i will check on that

thank you

[Geof]

Originally Posted by timmydabull what type of fluid would you reccomend? thank you

Whatever was in there originally, providing it was what the manufacturer recommended.

[Scanfab]

What TPI do you have on the blade, 6-8 per inch? Over 7 inches you have 50 teeth engaged with a cutting force of saw 100lbs, each tooth only cuts with 2 lbs-not enough to dig in a proper manner. Check what kind of chips leave the blade/part-dust and glitter?! Get a blade with only 2-4 teeth per inch, and no problems on a long engagment cut like that.

For long plate cuts of 12" I put 1" dia stock under the piece to be cut next to the solid jaw elevating the part to an angle. Band engagmennt is never more than 4-5 inches at any time, works like a charm. One inch lift will not cause the stock to pop up from the vice.

The saw is still a CNC machinists best machine- All my CNC machines are working against me, but at least the saw pulls to my side!!

[JoeFin]

Morse Variable Tooth blades work best for me

[HuFlungDung]

Originally Posted by Scanfab What TPI do you have on the blade, 6-8 per inch? Over 7 inches you have 50 teeth engaged with a cutting force of saw 100lbs, each tooth only cuts with 2 lbs-not enough to dig in a proper manner. Check what kind of chips leave the blade/part-dust and glitter?! Get a blade with only 2-4 teeth per inch, and no problems on a long engagment cut like that. For long plate cuts of 12" I put 1" dia stock under the piece to be cut next to the solid jaw elevating the part to an angle. Band engagmennt is never more than 4-5 inches at any time, works like a charm. One inch lift will not cause the stock to pop up from the vice. The saw is still a CNC machinists best machine- All my CNC machines are working against me, but at least the saw pulls to my side!!

I agree. Use a 3-4 varitooth. You should be able to cut that in under 5 minutes. My homemade bandsaw (only 1/2hp) will cut a 5" round in 5 minutes using a coarse blade like that, a bigger saw should be faster. Coolant is mandatory to prevent blade plugging when cutting a long drag.

Try adjusting the downfeed cylinder whilst cutting air. Determine what setting will allow the saw to descend within 5 minutes. Then cut for real at that setting. I wouldn't be surprised if you could be even more aggressive once you get the hang of it. The band should be okay at 400 fpm if it is bimetal.

[timmydabull]

thank you guys for your replies,now i know what i should expect in terms of cutting time feed speed etc.,i have a 2-3 blade from lenox coming in mon am,and i will check with the manufacture to see what fluid to use in the cylinder.

the blade i have in there now is a 5-8 starrett it broke and i ordered the 2-3 last week,i will order a vari tooth to start using once this blades has served its duty.

i have tried a few 3-4 but that was before i got the cylinder cleaned out and a new flow control valve installed and working sufficiently,so that may be why they might not have worked correctly.

once again thank your for your help and assistance.