When the plaintiff entered the defendant’s service, he impliedly agreed to assume all the obvious risks of the business, including the risk of injury from the kind of machinery then openly used. It is not material whether he examined the machinery before making his contract or not. He could look at it if he chose, or he could say, “ I do not care to examine it; I will agree to work in this mill, and I am willing to take my risk in regard to that.” In either case, he would be held to contract in reference to the arrangement and kind of machinery then regularly in use by his employer, so far as these things were open and obvious, so that they could readily be ascertained by such examination and inquiry as one would be expected to make if he wished to know the nature and perils of the service in which he was about to engage.
A projecting set screw is a common device for holding the collar on a shaft, although there is a safer kind of set screw in common use. Under its contract with the plaintiff the defendant owed him no duty to box the pulley or shaft, or to change *160the set screw for a safer one. Coombs v. New Bedford Cordage Co. 102 Mass. 572.
It is contended by the plaintiff that the defendant was negligent in not warning him of the danger. The rule of law invoked by the plaintiff applies only when there is a danger known, or -which ought to be known, to the employer, of which the employee through youth or inexperience is ignorant, and which the employee cannot reasonably be expected to discover by the exercise of ordinary care. In this case, although the set screw could not be seen when the shaft was revolving, it was plainly visible when the shaft was at rest; and while the screw doubtless increased somewhat the danger of being caught by contact with the shaft, belt, or pulleys, that danger was so obvious to every one, and was manifestly so great, that even the most ignorant person would endeavor to keep away from those parts of the machinery. The collar and set screw did not project much beyond the pulleys and belt, but were almost in their line of motion. Although the plaintiff says he did not know of the set screw, his testimony shows that he was well aware of the danger from the moving pulleys, belt, and shaft. He says in a variety of forms of expression that he was doing the best he could to keep clear of the pulleys, and that he was watching to protect himself as well as the hemp. He wras more than forty years of age, and had had considerable experience. There is nothing in the case to indicate that he needed any warning of the danger from coming in contact with this rapidly revolving machinery, whether he knew of the set screw or not. Indeed, if the defendant had warned him, he would merely have been told that there was great danger of getting caught if he came in contact with that part of the machinery, and that he must use his best effort to avoid it. But it is evident that he knew all that without warning. It has been held in many similar cases that the accident was not imputable to negligence of the defendant. Russell v. Tillotson, 140 Mass. 201. Ciriack v. Merchants' Woolen Co. 146 Mass. 182, and 151 Mass. 152. Goodnow v. Walpole Emery Mills, 146 Mass. 261. Crowley v. Pacific Mills, 148 Mass. 228. Coullard v. Tecumseh Mills, 151 Mass. 85. Pratt v. Prouty, 153 Mass. 333. Tinkham v. Sawyer, 153 Mass. 485. Henry v. King Philip Mills, 155 Mass. 361. De Souza v. Stafford *161Mills, 155 Mass. 476. Rood v. Lawrence Manuf. Co. 155 Mass. 590. Carey v. Boston & Maine Railroad, 158 Mass. 228. Hale v. Cheney, 159 Mass. 268.
The evidence of custom in other factories was immaterial. Assuming that it might have been competent as tending to show negligence of the defendant if the accident had happened to one there by invitation to do business with the defendant, it was of no consequence in view of the plaintiff’s implied contract to work with the machinery which the defendant was then using. Exceptions overruled.