Link belts used to be, and I assume still are, very stretchy indeed, when compared with a modern cut edge (and maybe notched) V belt, which have negligible stretch, and indeed, shrink in length if they get hot due to slipping (good feature, that one). On one hand link belts have the benefit that on such as a pillar drill with cone pulleys, you can stretch them enough to change speeds without slackening the adjustment. On the other hand, you cannot use them at anywhere near the power of a non stretchy one. Many years ago I tried to run a long link belt to drive a single cylinder compressor at low speed. It would only get over TDC for about the first 10 minutes after taking one or more links out. On that particular job, I gave up on belts as it was impossible to fit an endless one without taking the flywheel off an engine and fitted a chain drive instead. (For anybody interested, Dorman 2DWD engine in a 20/28 HP Simplex 2' gauge locomotive. The only available auxiliary drive is the pulley that normally drives the fan, mounted on the camshaft end, and tightly sandwiched between the flywheel and crankcase. I replaced the pulley with a sprocket to drive the compressor and mounted a pulley and sprocket on the compressor so the fan still went round.)
There are, so far as I know, 2 sorts of link belts. The old style held together with rivets or similar. The rivet heads sit deeper in the groove than a normal V belt, and while they are designed around the groove standards for new pulleys without bottoming out, the rivets tend to sit on the bottom of the groove once the pulley becomes a bit worn. At that point, friction disappears almost entirely. You can either get a new pulley or deepen the bottom of the groove to refresh the clearance. The other sort, of which I hasten to add, I have no experience, uses a T shaped extension of each link as the joining component. If you are trying to run link belt over a flat belt pulley, skidding and probably also pulley damage is highly likely.
Many years ago, British Rail trains were fitted with a lot of link belts on Diesel Multiple Units, driving the likes of fans, exhausters and dynamos. We also had them as a stores item to replace the V belts on loco hauled coaches and the trailer cars of DMUs that had axle driven alternators. These coaches were fitted with a spare set of normal V belts under a cover on the axle pulley, and you used those once the new ones fitted at each wheelset change expired. When the reserve set expired (I think the pulleys were 6 row) you had to resort to link belts unless you could find another excuse for taking the axle down to slip a set of endless belts (and spares if you had any sense) over the end.
Anybody who had a legitimate cause for walking the track, as I did when on call for breakdowns back in the late 70s / early 80s, could collect miles of the dam stuff that had fallen off trains.
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------ Original Message ------
From: "mike allen" <animal@...>
To: [email protected]
Sent: Monday, 26 Jun, 23 At 04:45
Subject: Re: [SouthBendLathe] Depth of cuts
Hows your spindle bearings ? Have you done the test by using a rod through the spindle hole & lifting the rod to see what your clearances are ? Whats your finished product look like ? Like everyone else says you should be able to do better than your getting right now . I've been using HSS inserts from H R Warner for years now & I have absolutely no problem getting 0.030 & sometimes more in most things except for some mystery metal I have ended up using . I'm using a regular v-belt on the countershaft motor to large pulley , & a composite flat belt on the cone pulleys . See if theres a industrial belting company in your neck of the woods & visit them & have them make you a belt . I think I paid 10 bucks for mine . The oil on your belts does need to get fixed somehow .
animal
On 6/25/23 8:32 PM, Mike Poore wrote:
.050 should be obtainable on a SB9.
If the belt is slipping, you should try to increase the tension first. Link belts are usually not a problem. Disconnect the belts and confirm that the spindle turns freely. Large diameter work is more likely to cause slipping due to the torque required. Try back gear for large diameter work.
On 6/25/2023 4:13 PM, Steven Schlegel wrote:
Wow. Lots of questions. One fact is really obvious. My machine operator pair should take cuts 10x deeper than I am.
The lathe head and all associated gearing is good. It was recently rebuilt and all pins, etc. were replaced correctly. Of that I am pretty certain. The drive unit moves freely, was also rebuilt, and operates correctly.
Speeds are from the ebay chart I bought. The HSS tools I grind are based upon lots of videos I watch. I bought a jig to help get the angles correct. My carbide are inserts, many are still the original chinesium, but are being replaced by higher quality as they die. I use a Boxer quick change toolpost.
Now, here is where I feel the problem lies since I do not have the power to make deep cuts:
I use a link belt on the motor. It slips especially as oil gets on it. The bearing in the drive unit slings oil. The drive belt to the lathe head is a serpentine auto belt. It seems to transfer power efficiently. The drive unit is mounted on channel so it's adjustable.
I am wondering about switching to an auto v-belt for the motor. Next, could the channel be flexing? It is the kind used to support conduit.
Thanks,
Steven
Get
What sort of carbide are you using? I've never had good luck with the 0 degree rake brazed carbide. I hear that it wants to run really fast.
On 6/25/23 14:24, Brandon Corey wrote:
0.002” is way too low. I run 0.015”-0.020” at a minimum for the hardest materials. Material? Speeds? What size is your motor?
Brandon
I have a simple question. How deep of cuts do you normally make?
I have a 1949 vintage SB9C, with 6 speeds. I replaced the 1/4 hp motor with a 1/2 HP one. I use carbide a lot, but HSS still gets used some. Many of the videos say I should take at least a 0.005" cut for the best finish. I usually cannot take more than 0.002" with dragging down, or stopping, the spindle.
What's reasonable for me?
Thanks, Steven
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