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Easy questions about my Grizzly 9729

Posted: Thu May 31, 2012 10:13 pm
by cjarrett
I'm pretty sure the answer is get a bigger vise, but I'll ask anyways.

Bought this machine, really happy with it so far, have learned a ton on it already. Have done mostly lathe work on it, but tried to do a bit of milling. I put a 3/16th end mill in an MT3 end mill holder, and with the headstock extended fully, I still cannot reach the peice I want to mill in the vise that came with the machine, I suppose this is because it wasn't intended to? With a bigger/taller vise I will be able to mill what I need?


Re: Easy questions about my Grizzly 9729

Posted: Thu May 31, 2012 11:12 pm
by Harold_V
Picture of setup?


Re: Easy questions about my Grizzly 9729

Posted: Fri Jun 01, 2012 12:38 am
by Torch
Unfortunately, a common problem with these. A taller vice is one option, but then what do you do when you have a taller piece to work on?

Another option would be a riser block, like this one: BusyBee elevating block. Personally, I went with this Shars tilt table which is the same 5" height, but has a larger surface with 3 slots and seems a bit sturdier. It's heavier, anyway. You could say it's more flexible, but that would be a really bad pun so I won't.

I would like to add that you should avoid milling with the quill extended whenever possible. Obviously, it is used for fine-tuning the depth of cut, but it's much more rigid when raised. I try to keep it in the top half of it's travel when milling. Faced with the choice, I'll mount the tilt table and raise the column rather than lower the quill to the bottom. That goes double for tiny endmills. I also make extensive use of an ER-40 collet chuck, which extends below the quill 4" or 5". Full extension of the quill is for drilling, IMHO.

Re: Easy questions about my Grizzly 9729

Posted: Fri Jun 01, 2012 12:50 am
by Torch
Oh, and BTW: the vise/lathe compound is a lousy milling vise. When you do buy a vise, get a decent milling vise. 4" size seems to be about perfect for these machines (since you only have 7" or 8" of travel anyway).

This 440V from Shars is excellent. It appears to be a house-branded Glacern GSV-440. Certainly more money than the cheap Chinese import clones, but far less than a Kurt and I doubt you would notice the difference. Not on milling with a 3-in-1, anyway.

If the Chinese (or Indian!) clone is all you can afford, then read this article about tuning them up to make them usable: "Polishing a Turd".

Re: Easy questions about my Grizzly 9729

Posted: Fri Jun 01, 2012 3:12 am
by cjarrett
Here is a picture of the setup, the current vise is 3.5" above the table. I like the idea of the adjustable angle table, is it easy to level and leave it there if needed? Also, do you just clamp your work to it or use a vise on it, or both?

Thanks again, already very valuable info for me.


Re: Easy questions about my Grizzly 9729

Posted: Fri Jun 01, 2012 9:09 am
by Torch
By "leave it there", do you mean leave the table set to level? If so, then yes. There's a pair of heavy clamp bolts underneath (one at each end) that you tighten when you have the angle set. If you mean leave the table on the cross-slide table, then no, there's not really enough room because of the limited cross-slide travel. Remember, you only have ~8" of travel, so to pass an endmill through a piece it has to be less than 4" in length with the vice centered. Less, actually, since you have to figure on the endmill diameter too.

Levelling is not too bad. The one that I bought (and linked to) has a worm-gear adjustment, which helps, although it is a bigger advantage when setting an angle than with leveling since the play in the gear will allow the table to flop past level under it's own weight. I find it useful to put a lump of metal on one side and bring the table up to level from that side, so as to keep the pressure on the one side of the gear. I also leave just a tiny bit of drag on the bolts.

I put a parallel on the clean table surface across the slots and hang a DTI with magnetic base from the mill head. Running the table back and forth under that confirms when it's dead level, since the angle gauge is a bit of a judgement call. Like your compound rotation, it's marked in degrees. You can approximate 1/2 a degree, maybe even 1/4 of a degree. But you'll never get that pretty double swirl finish out of a flycutter unless it's pretty much dead on. Finally, I tighten the clamp bolts evenly, about a 1/6 of a turn at a time to prevent anything from shifting while tightening it down. The entire procedure takes all of two minutes once you have the hang of it.

Speaking of compound adjustment, here's a really useful mod I did on mine:
I'm thinking of making one for the tilt table too.

Unfortunately, I don't seem to have a nice picture of the tilt table mounted on the machine. All my photos with the tilt table are closeups of what I'm making, not the table! So this will have to suffice for now:
That vice is my "magic jaws" vice, not the Shars I mentioned earlier. Great for holding irregular shaped objects, not very repeatable.

But since I'm posting photos, here's some of the Shars/Glacern to reference against the "Polishing a Turd" article.

Here's the casting that draws down the movable jaw, as it came:
The paint did interfere with smooth operation. Here it is after cleaning off the paint. Now it's smooth as glass:
It draws down quite nicely. Clamped on the 1-2-3 block over parallels, here's the force required to move the parallel:
And it's quite repeatable:
Overall, the tolerances of the unit I got are better than the published specs. Others report similar findings.

Re: Easy questions about my Grizzly 9729

Posted: Fri Jun 01, 2012 3:01 pm
by cjarrett
Thanks a lot, I actually found that same angle table locally at KBC and will probably pick that up and some 123 blocks too. When you notched the angle marks on your vice, did you use a rotary table and the mill? I should do that, as the angle guide on mine is garbage, held on by horrible rivets.

Re: Easy questions about my Grizzly 9729

Posted: Fri Jun 01, 2012 6:40 pm
by Torch
Ah, I see you've noticed the flaw in the original design. :D Yes, I used the RT and milled the marks after very carefully measuring everything to ensure I was properly zeroed.

I have happily made many modifications to my machine. Everything from gearing to the drive controllers. One could argue I should have bought a better machine in the first place, but I like to think of it as having bought a good starting point...

Re: Easy questions about my Grizzly 9729

Posted: Mon Jun 04, 2012 2:45 pm
by cjarrett
Very good, thanks.

Did you find you had to make any adjustments to the tailstock or table slides to make it true or accurate?

Re: Easy questions about my Grizzly 9729

Posted: Mon Jun 04, 2012 8:58 pm
by Torch
No, I carefully levelled the machine in the initial setup and adjusting the tailstock was pretty straightforward. The gibs do need to be carefully adjusted to ensure consistency without undue binding or friction, especially the table gibs. One of my modifications was to swap out the recessed allen-head table gib adjustment screws with long ones (made on the lathe :lol: ) complete with lock nuts, to make the process easier.

Best mod was to install a DTI. I don't know how anyone is expected to read the table wheel index ring when the cross-slide is hanging over it.

Tramming the head was a bit trickier, since there is no natural adjustment provided. But, loosening the 4 column mounting bolts allowed me to slide shims in the joint. It actually didn't take much -- I think I used 1.5 or 2 thou shim stock.

Other mods include:

Swapping out the SCR drive controller for a pair of PCM controllers for better torque at low rpms, and independent speed control of the motors. Now I can use the lathe motor as a drive when milling. Note that I ordered my machine with 1hp variable speed DC motors to begin with. As an added bonus, the motors run cooler, smoother and quieter. Guys talk about VFD drives for AC motors -- they are nothing but PCM controllers for AC motors. Whichever you have, get a PCM or VFD controller -- well worth the money.

As part of the above, I had to rewire the tachometer leads with shielded wire and ferrite choke cores. The high-frequency emmissions from the PCM and associated wiring were causing strange readings on the electronic tach!

Modified the lead screw protector to accommodate a threading dial. From the factory, it was one or the other but I wanted both.

Ground the 3-jaw chuck jaws for perfect concentricity.

Swapped in the stock tool post for a QCTP, and of course, mounted it on a plate to centre it on the table.

Re-worked the "Quick change gears" (a misnomer if there ever was one) to simplify things. Now I only have to swap the two easiest gears and it only takes 60 seconds or so. I call it my "rapid change" gearbox :lol: Note that I started with the HQ800V model, which came with an actual gear box on the lead screw for most range changes. The change gears are only necessary to switch between fine feed, metric threading and inch threading, the gear box sets the actual pitch. This is not a common accessory.

It was wearing out the half-nut and cross-slide nut with surprising rapidity. I polished the associated screw shafts -- the keyways left sharp edges which I think contributed to the wear rate.

Cut new headstock gears from aluminium to replace the nylon ones. Replaced the various steel keys and roll pins with copper shear pins/keys instead so I have easy to change designed failure points in case of a crash.

I ordered the machine with an R8 spindle, so this isn't exactly a mod, but they screwed up and shipped it with an MT3 so I had to swap in the R8 myself when they finally sent the correct one. I means more tooling, since the spindle and tailstock do not have the same taper, but there are some advantages to R8 for milling.

Added felt wipers to the table to keep chips and dust out of the sliding surfaces. I'm going to add them to the tailstock too, just need to get a "round tuit".

Another planned mod is to fabricate a new handwheel for the table crank. A larger diameter should help with fine adjustment. As it is right now, there's a bit of stiction when the table is loaded down with the weight of a rotab, 4-jaw and workpiece. A decent sized handwheel should give me better leverage and therefore control.

That's all I can think of off the top of my head. There may have been some other little tweaks along the way, but mostly just things light tightening bolts and adjustments.

Actually, I should mention that I beefed up the stand with some angle iron. It's still too flimsy for my taste and I will do something else eventually. For the interim, I just avoid any speeds that cause harmonic vibration.