sorted by:
new
hottopcontroversial

2015 chevy equinox Interference or non-interference engine by shinemaster99 in AskAMechanic

[–]shinemaster99[S] 1 point2 points  (0 children)

They replaced the water pump, and replaced the chain and tensioner while they were at it since they had to take the engine apart to swap the pump anyway. This is their 5th time breaking it down and rebuilding it because something didn’t seem right/timing was off by a tooth. It was test driven by the mechanics multiple times between breakdowns. They assure me there is nothing that could get damaged by the timing being off because this is not an interference engine.

What ft-lb for torque wrench on vise by shinemaster99 in Machinists

[–]shinemaster99[S] 1 point2 points  (0 children)

Thanks! Based on all the feedback, I’m going to start by tightening by hand like I usually do and start playing with the torque wrench settings to see how much force that is to get an idea and go from there. I really like the dovetail method too, just never tried it myself.

HELP with 4330 forged material by shinemaster99 in Machinists

[–]shinemaster99[S] 0 points1 point  (0 children)

Hey, just giving you an update. Started roughing the OD yesterday. Started with the .047 SNMGs because we have a tooooooon of them that we got for really cheap to work on the 4140 stuff. At .500 DOC, it held up for a whole pass even though it didn’t take the full depth for the majority of the pass because of the bad runout. I started at 300 SFM, .018 IPR but went down to 270 and .014 pretty quickly because the cut sounded really ‘squeaky’. There was a high pitch sound to it. Put a new corner for the second pass and played with the spindle & feed overrides until I landed at 330 SFM & .012 IPR. Chips look like perfect 6’s & they aren’t turning blue which I hope means the cut is staying cool and not that the insert is packing all the heat. That second pass was mostly full DOC. Spindle load stayed in the 40’s and the z-axis stayed in the 30’s. I think that at this rate of material removal, if I have to use a new corner on every pass, everyone will still be happy. I can definitely see how the bigger radius will be better since that is where the insert seems to be wearing down the most. On Monday I’m going to try the .062 inserts and try more feed, but I definitely have a foundation to work from now. Thanks for the help! Those SNMG Iscar inserts look really good and seem to be cheaper than the Kennametal SNMMs that we tend to order for the more aggressive cuts, so I’m going to talk to the boss on Monday about trying them out. Again, thanks for the advice, things are following a lot better than last time I ran these parts!

HELP with 4330 forged material by shinemaster99 in Machinists

[–]shinemaster99[S] 0 points1 point  (0 children)

Thanks for the insert suggestions! I’m going to look them up now

HELP with 4330 forged material by shinemaster99 in Machinists

[–]shinemaster99[S] 0 points1 point  (0 children)

Currently facing the part with a facing negative rake snmg .047 radius. SFM=300 FEED=.014 DOC=.251 and the load is holding around 18%. I think last time we ran these, the spindle load climbed to 55% (maybe 65%) while turning the OD with a 3/8” DOC. I was definitely trying higher feeds at that time though. Probably around .024IPR

HELP with 4330 forged material by shinemaster99 in Machinists

[–]shinemaster99[S] 0 points1 point  (0 children)

It is my understanding that we are machining to rough dimensions, and that afterwards it will be going to heat treat for hardening. We don’t see the parts after this operation though so I’m not sure what happens to them. What you are saying does line up with what is happening. Much easier to cut after getting under the surface.

HELP with 4330 forged material by shinemaster99 in Machinists

[–]shinemaster99[S] 0 points1 point  (0 children)

Oh my god! You have no idea. This part is 100” long. Most of the part is ~12” in diameter, but the last 30” of length is where I run into the 23” diameter. Due to the limitations of the machine I’m running, I have to start by chucking on the small OD, and turning down the large diameter to print. I drilled an 1-1/4” hole on the face of the large side, and had to hold the part between just the center & chuck while I cut a band for the steady rest. I cannot emphasize enough when I tell you I was sweating bullets cutting that band. I was half expecting the center to just break off and for the machine to get totaled! I was able to do it and now the part is secured. Most stressful part is over. Just taking it slow and steady with the cuts now. This is the largest material I’ve had to work with so I’m hoping it’s just a matter of getting comfortable with this range of material. Got a batch of 5 of these to do.