Getting my new G9729 Grizzly up running! Help

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Harold_V
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Re: Getting my new G9729 Grizzly up running! Help

Post by Harold_V »

LX Kid wrote:My parts came in the mail this morning and I reassembled the parts into the lathe. "Crappy Parts!" The gear w/shaft was also just as rough made as the first one without the rust.
Assuming that the portion of the shaft that is a bearing surface isn't rough, that's likely not an issue, as this piece of the machine lends nothing towards precision. I'm not suggesting that being rough is acceptable, just that a rough one will perform just fine. All it is intended to do is propel the carriage, which it can do without issue.
I also had to drill my own roll pin hole!
That's so the required hole will line up. It's not easy drilling through preexisting holes and remain aligned, especially if the hole must be hand drilled. By creating the hole in its entirety, you'll assured that the pin will fit as required. Imagine the results of drilling through the shaft, which now becomes a guide, and you have missed the centerline of the exit hole.

It would be my opinion that spending time and effort on another gear would have benefit only in becoming a learning experience. I fully expect that a new one won't provide any better service.

Harold
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LX Kid
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Re: Getting my new G9729 Grizzly up running! Help

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Nothing wrong with wanting the best smoothness you can get out of a cheap lathe. Identify a personal irritant and fix it to the best of your ability is always a nice challenge. I'll bet I'm not the only one that dislikes the carriage shuttle roughness.
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Re: Getting my new G9729 Grizzly up running! Help

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Unless the gear is running under a stressed condition, it isn't likely that a new gear will improve the feel. I'm assuming that there's some clearance between the rack and gear. If there isn't, then, yeah, you are likely to witness a difference.

Don't misunderstand. I'm all for improving the performance of a machine--any machine---but some things simply don't make a difference (paint, for an excellent example). There are better things to pursue if you hope to improve the machine.

Harold
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LX Kid
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Re: Getting my new G9729 Grizzly up running! Help

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Harold_V wrote:Unless the gear is running under a stressed condition, it isn't likely that a new gear will improve the feel. I'm assuming that there's some clearance between the rack and gear. If there isn't, then, yeah, you are likely to witness a difference.
Don't misunderstand. I'm all for improving the performance of a machine--any machine---but some things simply don't make a difference (paint, for an excellent example). There are better things to pursue if you hope to improve the machine.
Harold
Still trying to find them one-by-one. Haven't made my first cut with it yet! Tomorrow I'm going to drain the headstock oil and see what it looks like. Probably put 30w non-detergent oil back in.

The squared off tips of the rack teeth may also be causing some "herky-jecky" action of the hand wheel.

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Re: Getting my new G9729 Grizzly up running! Help

Post by Torch »

The rack teeth look like the right profile. Gear teeth are curved because the gear is curved -- the curve profile varies by the number of teeth. The curve of teeth on small gears is more pronounced than on large gears. Is it possible that the rack is mounted a hair too low, causing the gears to bind?
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Re: Getting my new G9729 Grizzly up running! Help

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Torch wrote:The rack teeth look like the right profile. Gear teeth are curved because the gear is curved -- the curve profile varies by the number of teeth. The curve of teeth on small gears is more pronounced than on large gears. Is it possible that the rack is mounted a hair too low, causing the gears to bind?
I was thinking of maybe adding .002" shim stock between the gear box and the cross-slide base to see what the results might be. Today I made a metal tray under the machine to catch chips, oil, etc.

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Last edited by LX Kid on Fri May 01, 2015 4:20 pm, edited 1 time in total.
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Re: Getting my new G9729 Grizzly up running! Help

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What can I do, rather than buying ready made, to protect the lead screw from chips, grit, etc? Anyone have a DIY idea that they have done? I've seen those collapsable ones but they are rather expensive for a 36" lathe bed.
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Re: Getting my new G9729 Grizzly up running! Help

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I ran paper strips between the spur gear and the rack and discovered that it was pinching at back of the rack. I put .004" shims on the back side of the the apron gear box and it leveled the gear somewhat and runs much better back and forth. For now I'll quit "whining" about rough workings even though it's still there due to the pitted spur gear.

Guess it's time to start thinking about my first project. Being that I invested $500, several years ago, in a dividing head I may study gears and gear making. Bought some pretty good books off Amazone and going to do some reading if my family will leave me alone long enough! LoL The older I get I find it's getting harder to concentrate and retain information.
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LX Kid
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Re: Getting my new G9729 Grizzly up running! Help

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I found a brass rifle cleaning rod to make a pin for the lead screw drive. When I machined it down I found that it was pretty stout metal. Are there alloy brass metals that l'm not aware of? I thought brass is brass. Maybe I should look around for some softer brass. It seems that this metal is no better protection than the steel roll pin I removed.
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Re: Getting my new G9729 Grizzly up running! Help

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Yes, there are different kinds of brass. However, the shear strength of free-machining brass is approximately 60% of a free-machining steel (eg: 12L14), and perhaps 15-20% of a good spring steel. Of course, a spring steel roll pin will have less material but it's still going to be tougher and less likely to shear than a brass pin.
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Re: Getting my new G9729 Grizzly up running! Help

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LX Kid wrote: Are there alloy brass metals that l'm not aware of? I thought brass is brass.
Indications are you are clueless where copper alloys are concerned (no, I'm not trying to be rude, although it may appear that I am).

It may be beyond an individual's ability to discern brass from bronze, the names of which are generally used interchangeably, although improperly. It doesn't help that the very thing that separates the two (brass is typically a zinc/copper alloy, while bronze is a tin/copper alloy) isn't consistent, as some alloys contain both elements.

To assume that "brass" is of lower strength than steel isn't sound, as there are alloys that are far stronger; one of which would be Copper Alloy No. C86300, with a tensile strength of approximately 150% of mild steel.
Maybe I should look around for some softer brass. It seems that this metal is no better protection than the steel roll pin I removed.
If you're hoping to use a material that is readily shorn, why not turn to aluminum (6061, for example)? It's far less expensive and can be easily softened, further lowering its shear strength. You are most likely to encounter this material in the T-6 state, about 2/3 the tensile of steel). Avoid the 7000 series, as it tends to rival steel in tensile strength.

Harold
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LX Kid
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Re: Getting my new G9729 Grizzly up running! Help

Post by LX Kid »

Harold_V wrote:
LX Kid wrote: Are there alloy brass metals that l'm not aware of? I thought brass is brass.
Indications are you are clueless where copper alloys are concerned (no, I'm not trying to be rude, although it may appear that I am).

It may be beyond an individual's ability to discern brass from bronze, the names of which are generally used interchangeably, although improperly. It doesn't help that the very thing that separates the two (brass is typically a zinc/copper alloy, while bronze is a tin/copper alloy) isn't consistent, as some alloys contain both elements.

To assume that "brass" is of lower strength than steel isn't sound, as there are alloys that are far stronger; one of which would be Copper Alloy No. C86300, with a tensile strength of approximately 150% of mild steel.
Maybe I should look around for some softer brass. It seems that this metal is no better protection than the steel roll pin I removed.
If you're hoping to use a material that is readily shorn, why not turn to aluminum (6061, for example)? It's far less expensive and can be easily softened, further lowering its shear strength. You are most likely to encounter this material in the T-6 state, about 2/3 the tensile of steel). Avoid the 7000 series, as it tends to rival steel in tensile strength.

Harold
Good idea! I was just trying to find anything I could lay my hands on to replace the pin. Aluminum may be a better choice. I think I know where a broken aluminum rifle cleaning rod is that I can make a pin.
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