DPittman
Ultra Member
So I think I tried to figure this out when I went vfd but I don't remember what my results were....Are there and dangers (equipment wise) to running too low of Hz?
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What Projects Are You Considering This Winter?
- Thread starter CalgaryPT
- Start date
I believe running the motor at too low or too high Hz for an extended period of time can cause the motor to over heat.
DPittman
Ultra Member
Ah that's ringing a bell. I remember that going too high certainly could be a problem but that running at 120hz was for sure safe as the motor construction between the 1700 and 3400 rpm motors was the same. And I guess it makes sense that if the motor isn't turning fast enough the fan may not be effective. However if you are running really slow maybe the load isn't that high anyhow.
That business of 3400 rpm Motors being the same as 1750 Motors is motor specific not generic. You shouldn't assume that is the case at all.
I also don't think it's safe to assume that the load isn't that high at low rpms. It may in fact be much higher because the end mill teeth can grab if they are not going fast enough.
The rule of thumb that I have seen suggest that the minimum speed and maximum speeds are more like 40hz and 75 hz for non vfd rated Motors. VFD rated Motors will specify these speeds right on the motor plate. Mine is 0 to 120.
Gearhead88
Super User
Like most of you , I have a list of things to do and stuff to build , the list never really gets smaller . This list has enough on it to keep me busy , when I get spare time.
I just started another engine rebuild on a 44 year old Shovelhead 1200 , that's going well , I did a couple of re-bores on the Van Norman , they were already + .010" oversize , it is going to +.020" over bore and finished on the Sunnen hone.
Lot's of wear on several items , the rods were not straight and were out of round , The beauty of old Harley engines is , if you have Sunnen hone you can hone the rods to make them straight again and use oversize rollers to hand "fit" the big end , this set straightened out nice at .0005" over the size they were. You can get several sizes of oversize rollers starting at +.0002" , in .0002" increments all the way up to +.001" and then the sizes go to steps of +.002" & +.003" . The crank pins come in a few sizes too if you need to hone the rod races out larger to straighten them or make them round again . You can also press in new races and go back to standard if that's what you want to do , the possibilities are huge ! . The small end bushings were bad too , rebuilding rods involves pressing in new bushings and honing them to fit the wrist pins . Back in the past this used to be common , guys having engines rebuilt like this , labour was not super expensive like it is now , parts were reasonable too , then labour rates climbed up & up . People then turned to crate engines and rebuilds became not so much an every day thing. Now parts are very expensive , lots of stuff is double what it was 5 - 10 years ago. The skills to do this kind of work are not easily found today , think about it , who even does a valve job anymore ?
The crank is supported on the left side in two Timken bearings which also control end play . The rh main bearing is a caged double roller arrangement .
The outer race , if it gets out of round or develops a taper can be lapped back into a serviceable dimension and oversize rollers fit . You can also change that shaft or bearing race .
This is the lapping tool , it pilots off the left main , it's cranked by hand and is adjusted to size by two nuts that draw the lap head on to a taper and expand it.
One item on the list is to restore this valve spring tester , I may reach out to Rimac to get a new lens and bezel .
I need to take it completely apart and de-rust a few things , paint it and get a calibration spring .
I just started another engine rebuild on a 44 year old Shovelhead 1200 , that's going well , I did a couple of re-bores on the Van Norman , they were already + .010" oversize , it is going to +.020" over bore and finished on the Sunnen hone.
Lot's of wear on several items , the rods were not straight and were out of round , The beauty of old Harley engines is , if you have Sunnen hone you can hone the rods to make them straight again and use oversize rollers to hand "fit" the big end , this set straightened out nice at .0005" over the size they were. You can get several sizes of oversize rollers starting at +.0002" , in .0002" increments all the way up to +.001" and then the sizes go to steps of +.002" & +.003" . The crank pins come in a few sizes too if you need to hone the rod races out larger to straighten them or make them round again . You can also press in new races and go back to standard if that's what you want to do , the possibilities are huge ! . The small end bushings were bad too , rebuilding rods involves pressing in new bushings and honing them to fit the wrist pins . Back in the past this used to be common , guys having engines rebuilt like this , labour was not super expensive like it is now , parts were reasonable too , then labour rates climbed up & up . People then turned to crate engines and rebuilds became not so much an every day thing. Now parts are very expensive , lots of stuff is double what it was 5 - 10 years ago. The skills to do this kind of work are not easily found today , think about it , who even does a valve job anymore ?
The crank is supported on the left side in two Timken bearings which also control end play . The rh main bearing is a caged double roller arrangement .
The outer race , if it gets out of round or develops a taper can be lapped back into a serviceable dimension and oversize rollers fit . You can also change that shaft or bearing race .
This is the lapping tool , it pilots off the left main , it's cranked by hand and is adjusted to size by two nuts that draw the lap head on to a taper and expand it.
One item on the list is to restore this valve spring tester , I may reach out to Rimac to get a new lens and bezel .
I need to take it completely apart and de-rust a few things , paint it and get a calibration spring .
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Gearhead88
Super User
Here's the thing with Harley engines , you never know what kind of ham fisted BS has occurred in it's life , what level of care and servicing it had or what kind of meat heads have worked on it , this can have a huge impact on aging .
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Brent H
Ultra Member
@Gearhead88 : I am in the process of rebuilding a 1970 Opel GT. Engine parts all came in and now it will be all up to some good old fashion work of cutting valve seats, porting the head, all new bearings and seals and fitting new pistons etc etc
I will be testing my springs on the mill using a calibrated refrigerant scale and the mill's DRO for compression distance - should be fun !!
I will be testing my springs on the mill using a calibrated refrigerant scale and the mill's DRO for compression distance - should be fun !!
Dan Dubeau
Ultra Member
Good thread. The big project on my list is getting my shop organized and funcitonal. Almost there. Then I have a long list of things I want to build. Right now I'm working on a ribbon burner forge, and some other blacksmithing stuff. I'm also building a bandsaw mill, and need to get started on carriage at some point before the spring. I have a list a mile long.....Projects get added at about a 4:1 ratio to completion.
Way too close to home.You say "44 year old" like that's actually old, it was only 1978
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Chicken lights
Forum Pony Express Driver
You need a valve grinder, too? I have one if you need one, there’s a bunch of stones with it
Brent H
Ultra Member
@Chicken lights : do you have a valve seat cutter for doing the head? The manufacturer does not recommend lapping in the seats as the head is Alumetized. I am in the debate about cutting in hardened exhaust seats or just cleaning things up........
Chicken lights
Forum Pony Express Driver
It’s not mine, but yes I have a real valve grinding machine, for doing heads
Me too. I was already married with kids in 1978. Celebrated my 50th this past year.
Gearhead88
Super User
This spring tester is an inexpensive alternative to a Rimac , it's been my go to tool for a long time
Gearhead88
Super User
In case anyone was wondering , this is the rod bearing arrangement in a Harley crank . The crankshaft is called a flywheel or set of flywheels . Older versions , prior to 1985 had several pieces that made up the assembly , two flywheels , a sprocket shaft which is the drive side , a pinion shaft which drives the camshaft , oil pump and timed breather gear and the crank pin which supports the connecting rods . These can be disassembled for service and are totally rebuildable , shafts can be replaced with standard or oversized parts , roller bearings are available in several over sizes , .0002" , .0004" , .0006", .0008" , .001" ,.002" . There is huge support in the aftermarket for these parts , you can buy economy budget priced parts , regular duty stock equivilant or supreme heavy duty . 1985 & up have the shafts forged to the flywheels but the crank pin and rods could still be serviced and rebuilt , they were still assembled on tapers . From 1999 onward the manufacturer went to a pressed together flywheel that is pretty much a throwaway , very few shops rebuild them , you just buy a new one . Sadly , the quality of the newer cranks is not all that great , they can easily go out of true , the shafts , bearings and rods are a bit larger but the heat treat and materials used are not on the same level as older parts . Our Society has accepted a throw it away and get a new one mentality.
Brent H
Ultra Member
@Susquatch - that is the debate right now - can machine out for new seats - they are sitting at home. Or see what the original seats need cutting to. The original head is a Chromium grey cast iron and the exhaust seat area was hardened by the factory. The head is also alumetized.
I don't know if the seats are satellite - that would mean they are already cut to the proper angle. These are basic rings of hardened steel and need finishing. I am in the process to find out the materials. May need to see @Chicken lights to gett'er done
@Gearhead88 : that was an alternative plan for the springs. I may build one. I am also in the middle of building a bead roller and some other things. Just completed my cam bearing remover....so many neato projects
I don't know if the seats are satellite - that would mean they are already cut to the proper angle. These are basic rings of hardened steel and need finishing. I am in the process to find out the materials. May need to see @Chicken lights to gett'er done
@Gearhead88 : that was an alternative plan for the springs. I may build one. I am also in the middle of building a bead roller and some other things. Just completed my cam bearing remover....so many neato projects
I purchased a Neway valve seat cutter for the Ford NAA tractor rebuild. Very well made, great people to deal with (dealt directly through Neway, no ebay/knockoffs etc.).